View source for Japanese aircraft carrier Kaga

{{short description|Aircraft carrier of the Imperial Japanese Navy}}
{{other ships|Japanese ship Kaga}}
{{Use dmy dates|date=December 2020}}
{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=Japanese Navy Aircraft Carrier Kaga.jpg
|Ship caption=''Kaga'' after her modernization, with her distinctive downward-facing [[funnel (ship)|funnel]]
}}
{{Infobox ship class overview
| Name =
| Operators = {{navy|Empire of Japan}}
| Class before = {{ship|Japanese aircraft carrier|Akagi||2}}
| Class after = {{ship|Japanese aircraft carrier|Ryūjō||2}}
| Cost =
| Built range = 1920–1928
| In service range = 1928–1942
| In commission range = 1928–1942
| Total ships completed = 1
| Total ships lost = 1
}}
{{Infobox ship career
| Hide header =
| Ship country = [[Empire of Japan|Japan]]
| Ship flag = {{shipboxflag|Empire of Japan|naval}}
| Ship name = ''Kaga''
| Ship namesake = [[Kaga Province]]
| Ship ordered =
| Ship awarded =
| Ship builder = [[Kawasaki Heavy Industries|Kawasaki]] and [[Yokosuka Naval Arsenal]]
| Ship original cost = [[Japanese yen|¥]]53&nbsp;million ([[United States dollar|$]]36.45&nbsp;million)<ref>Parshall and Tully, p. 535</ref>
| Ship yard number =
| Ship way number =
| Ship laid down = 19 July 1920
| Ship launched = 17 November 1921
| Ship sponsor =
| Ship christened =
| Ship completed = 31 March 1928
| Ship commissioned = 30 November 1929
| Ship reclassified = 21 November 1923 as an aircraft carrier
| Ship refit = 20 October 1933&nbsp;– 25 June 1935
| Ship struck = 10 August 1942
| Ship fate = Sunk by [[dive bombers]] from the [[USS Enterprise (CV-6)|USS ''Enterprise'']] during the [[Battle of Midway]], 4 June 1942
}}
{{Infobox ship characteristics
| Hide header =
| Header caption = (after 1935 modernization)
| Ship class =
| Ship type = [[Aircraft carrier]]
| Ship displacement = {{convert|38200|LT|MT|0|lk=on}} ([[Displacement (ship)#Standard displacement|standard]])
| Ship length = {{convert|247.65|m|ftin|abbr=on}}
| Ship beam = {{convert|32.5|m|ftin|abbr=on}}
| Ship draft = {{convert|9.48|m|ftin|abbr=on}}
| Ship power = *8 Kampon [[water-tube boiler]]s
* {{cvt|127400|shp|kW|lk=on}}
| Ship propulsion = 4 shafts; 4 geared [[steam turbine]]s
| Ship speed = {{convert|28|kn|lk=in}}
| Ship range =
| Ship endurance = {{convert|10000|nmi|abbr=on|lk=in}} at {{convert|15|kn}}
| Ship complement = 1,708 (after reconstruction)
| Ship crew =
| Ship armament = *10 × single [[20 cm/50 3rd Year Type naval gun|{{convert|200|mm|abbr=on}} guns]]
* 8 × twin [[12.7 cm/40 Type 89 naval gun|{{convert|127|mm|in|0|abbr=on}}]] [[DP gun]]s
* 11 × twin [[Type 96 25&nbsp;mm AT/AA Gun|Type 96 {{convert|25|mm|in|abbr=on|0}}]] [[AA gun]]s
| Ship armor = *[[Belt armor|Belt]]: {{convert|152|mm|in|0|abbr=on}}
* [[Deck (ship)|Deck]]: {{convert|38|mm|in|abbr=on}}
| Ship aircraft = *90 (total); 72 (+ 18 in storage) (1936)
* 21 [[Mitsubishi A6M Zero]],
* 27 [[Aichi D3A]],
* 27 [[Nakajima B5N]] (7 Dec 1941)
| Ship aircraft facilities =
| Ship notes =
}}
|}
{{Nihongo|'''''Kaga'''''|加賀|lead=yes||named after the ancient [[Kaga Province]]}} was an [[aircraft carrier]] built for the [[Imperial Japanese Navy]] (IJN). Originally intended to be one of two {{sclass|Tosa|battleship|2}}<nowiki/>s, ''Kaga'' was converted under the terms of the [[Washington Naval Treaty]] to an aircraft carrier as the replacement for the battlecruiser {{ship|Japanese battlecruiser|Amagi||2}}, which had been irreparably damaged during the [[1923 Great Kantō earthquake]]. ''Kaga'' was rebuilt in 1933–1935, increasing her top speed, improving her exhaust systems, and adapting her flight decks to accommodate more modern, heavier aircraft.

The ship figured prominently in the development of the IJN's carrier striking force doctrine, which grouped carriers together to give greater mass and concentration to their air power. A revolutionary strategic concept at the time, the employment of the doctrine was crucial in enabling [[Empire of Japan|Japan]] to attain its initial strategic goals during the first six months of the [[Pacific War]].

''Kaga''{{'}}s aircraft first supported Japanese troops in [[Republic of China (1912–1949)|China]] during the [[28 January Incident|Shanghai Incident]] of 1932 and participated in the [[Second Sino-Japanese War]] in the late 1930s. With other carriers, she took part in the [[attack on Pearl Harbor]] in December 1941 and the [[battle of Rabaul (1942)|invasion of Rabaul]] in the Southwest Pacific in January 1942. The following month her aircraft participated in a [[Bombing of Darwin|combined carrier airstrike]] on [[Darwin, Northern Territory|Darwin]], Australia, and helping secure the [[Dutch East Indies campaign|conquest]] of the [[Dutch East Indies]] by Japanese forces. She missed the [[Indian Ocean raid]] in April as she had to return to Japan for repairs after hitting a [[reef]] in February.

Following repairs, ''Kaga'' rejoined the [[1st Air Fleet of the Imperial Japanese Navy|1st Air Fleet]] for the [[Battle of Midway]] in June 1942. After bombarding American forces on [[Midway Atoll]], ''Kaga'' and three other IJN carriers were attacked by American aircraft from Midway and the carriers {{USS|Enterprise|CV-6|2}}, {{USS|Hornet|CV-8|2}}, and {{USS|Yorktown|CV-5|2}}. [[Dive bomber]]s from ''Enterprise'' severely damaged ''Kaga''; when it became obvious she could not be saved, she was [[scuttling|scuttled]] by Japanese [[destroyer]]s to prevent her from falling into enemy hands. The loss of ''Kaga'' and three other IJN carriers at Midway was a crucial setback for Japan, and contributed significantly to Japan's ultimate defeat. In 1999, debris from ''Kaga'' including a large section of her [[hull (watercraft)|hull]] was located on the ocean floor northwest of Midway Island.<ref>Nauticos</ref> In 2019, {{RV|Petrel}} discovered her wreck on the ocean floor.

==Design and construction==
{{See also|Tosa-class battleship}}
''Kaga'' was laid down as a {{sclass|Tosa|battleship|2}}, and was launched on 17 November 1921 at the [[Kawasaki Heavy Industries]] shipyard in [[Kobe]]. On 5 February 1922 both ''Tosa''-class ships were canceled and scheduled to be [[scrap]]ped under the terms of the [[Washington Naval Treaty]].<ref>Gardiner and Gray, p. 232; Jentschura, p. 35</ref>

The Treaty authorized conversion of two battleship or battlecruiser hulls into aircraft carriers of up to {{convert|33000|LT|t|lk=on}} standard displacement. The incomplete [[Amagi-class battlecruiser|battlecruisers ''Amagi'']] and {{ship|Japanese aircraft carrier|Akagi||2}} were initially selected, but the [[1923 Great Kantō earthquake|Great Kantō earthquake]] of 1923 damaged ''Amagi''{{'}}s hull beyond economically feasible repair, and ''Kaga'' was selected as her replacement. The formal decision to convert ''Kaga'' to an aircraft carrier was issued 13 December 1923, but no work took place until 1925 as new plans were drafted and earthquake damage to the [[Yokosuka Naval Arsenal]] was repaired. She was officially commissioned on 31 March 1928, but this signified only the beginning of sea trials. She joined the [[Combined Fleet]] (''Rengō Kantai'') on 30 November 1929 as the IJN's third carrier to enter service, after {{ship|Japanese aircraft carrier|Hōshō||2}} (1922) and ''Akagi'' (1927).<ref name=l8>Lengerer, p. 128</ref>

''Kaga'' was completed with a length of {{convert|238.5|m|ftin|sp=us}} [[length overall|overall]]. She had a [[beam (nautical)|beam]] of {{convert|31.67|m|ftin|sp=us}} and a [[draft (ship)|draft]] at full load of {{convert|7.92|m|ft|sp=us|0}}. She displaced {{convert|26900|LT|MT}} at [[Displacement (ship)#Standard displacement|standard]] load, and {{convert|33693|LT|MT}} at [[full load]], nearly {{convert|6000|LT|MT}} less than her designed displacement as a battleship.<ref name=l9>Lengerer, p. 129</ref>  Her complement totaled 1,340 crewmembers.<ref>Jentschura, p. 42</ref>

===Flight deck arrangements===
[[File:Kaga Ikari 1930 B.jpg|thumb|left|''Kaga'' as completed, with all three flight decks visible]]
''Kaga'', like ''Akagi'', was completed with three superimposed flight decks, the only carriers ever to be designed so. The British carriers converted from "large light cruisers", {{HMS|Glorious|77|2}}, {{HMS|Courageous|50|2}}, and {{HMS|Furious|47|2}}, each had two flight decks, but there is no evidence that the Japanese copied the British model. It is more likely that it was a case of the parallel designs converging in separate attempts to improve [[launch and recovery cycle]] flexibility by allowing simultaneous launch and recovery of aircraft.<ref>Brown, p. 2</ref> ''Kaga''{{'}}s main flight deck was {{convert|171.2|m|ftin|sp=us}} long and {{convert|100|ft|m|order=flip|1|sp=us}} wide,<ref>Peattie, p. 231</ref> her middle flight deck was only about {{convert|15|m|ftin|sp=us}} long and started in front of the bridge, and her lower flight deck was approximately {{convert|55|m|ftin|sp=us}} long. The utility of her middle flight deck was questionable as it was so short that only some of the lightly loaded aircraft could use it, even in an era when the aircraft were much lighter and smaller than they were during World War II.<ref>Lengerer, pp. 130, 134</ref> The ever-increasing growth in aircraft performance, size and weight during the 1930s meant that even the bottom flight deck was no longer able to accommodate the take-off roll required for the new generations of aircraft being fielded and it was plated over when the ship was modernized in the mid-1930s.<ref>Lengerer, pp. 130, 136</ref>  ''Kaga'' lacked an [[Glossary of nautical terms (A-L)#island|island]] until one was added during the modernization.<ref>Peattie, pp. 54–55</ref>

As completed, the ship had two main hangar decks and a third auxiliary hangar with a total capacity of 60 aircraft. The hangars opened onto the middle and lower flight decks to allow aircraft to take off directly from the hangars while landing operations were in progress on the main flight deck above. No catapults were fitted.<ref name="ireland"/> Her forward [[Elevator#Aircraft elevators|aircraft elevator]] was offset to starboard and {{convert|10.67|by|15.85|m|ft|sp=us|0}} in size. Her aft elevator was on the centerline and {{convert|12.8|by|9.15|m|ft|sp=us|0}}. Her [[arresting gear]] was a French transverse system as used on their aircraft carrier {{ship|French aircraft carrier|Béarn||2}} and known as the Model Fju (''Fju shiki'') in the Japanese service.<ref name=l34/> As originally completed, ''Kaga'' carried an air group of 28 [[Mitsubishi B1M|Mitsubishi B1M3 torpedo bombers]], 16 [[Nakajima A1N]] fighters and 16 [[Mitsubishi 2MR]] reconnaissance aircraft.<ref name=l9/><ref group=Note>Hata, p. 24, gives the carrier's initial aircraft complement as 12 Type 3 fighters (plus three crated spares), six reconnaissance aircraft (with two spares), and 18 torpedo bombers (six spares).</ref>

===Armament and armor===
[[File:Japanese Navy Aircraft Carrier Kaga 1928.jpg|thumb|right|''Kaga'' [[fitting-out]] in 1928. This stern view shows the long funnel extending aft below the flight deck, and three 200 mm guns in casemates.]]
''Kaga'' was armed with ten [[20 cm/50 3rd Year Type naval gun|{{cvt|20|cm|1}} 3rd Year Type guns]], one twin-gun Type B turret on each side of the middle flight deck and six in [[casemate]]s aft. They fired {{convert|110|kg|lb|adj=on}} projectiles at a rate of three to six rounds per minute with a [[muzzle velocity]] of {{convert|870|m/s|ft/s|abbr=on}}; at 25°, they had a maximum range between {{convert|22600|and|24000|m|yd|abbr=on}}. The Type B turrets were nominally capable of 70° elevation to provide additional [[anti-aircraft warfare|anti-aircraft]] (AA) fire, but in practice the maximum elevation was only 55°. The slow rate of fire and the fixed 5° loading angle minimized any real anti-aircraft capability.<ref>Campbell, p. 187</ref> This heavy gun armament was provided in case she was surprised by enemy cruisers and forced to give battle, but her large and vulnerable flight deck, hangars, and other features made her more of a target in any surface action than a fighting warship. Carrier doctrine was still evolving at this time and the impracticability of carriers engaging in gun duels had not yet been realized.<ref>Peattie, pp. 53, 55</ref><ref group=Note>The [[United States Navy]] did much the same with the provision of four twin {{convert|8|in|adj=on|0}} gun turrets on their {{sclass|Lexington|aircraft carrier|0}} carriers. See Gardiner and Grey, p. 110.</ref>

She was given an anti-aircraft armament of six twin {{convert|12|cm|adj=on|sp=us}} 10th Year Type Model A2 gun mounts fitted on [[sponson]]s below the level of the funnels, where they could not fire across the flight deck, three mounts per side.<ref>Lengerer, p. 131</ref> These guns fired {{convert|20.3|kg|lb|adj=on}} projectiles at a muzzle velocity of {{convert|825|-|830|m/s|ft/s|abbr=on|0}}; at 45° this provided a maximum range of {{convert|16000|m|yd|sp=us}}, and they had a maximum ceiling of {{convert|10000|m|ft|sp=us}} at 75° elevation. Their effective rate of fire was 6 to 8 rounds per minute.<ref>Campbell, p. 194</ref> She had two Type 89 directors to control her 20&nbsp;cm guns and two Type 91 manually powered anti-aircraft directors (''Kōshaki'') to control her 12&nbsp;cm guns.<ref>Parshall and Tully, pp. 140, 467</ref> ''Kaga''{{'}}s [[Belt armor|waterline armored belt]] was reduced from {{convert|280|to|152|mm|in|0|abbr=on}} during her reconstruction and the upper part of her [[Anti-torpedo bulge|torpedo bulge]] was given {{convert|127|mm|in|0|abbr=on}} of armor. Her [[Deck (ship)|deck armor]] was also reduced from {{convert|102|to|38|mm|in|0|abbr=on}}.<ref name=l34>Lengerer, p. 134</ref>

===Propulsion===
[[File:Kaga Tateyama Trials 1928.jpg|thumb|''Kaga'' undergoing post-launch trials off Tateyama, 15 September 1928]]
When ''Kaga'' was being designed, the problem of how to deal with exhaust gases in carrier operations had not been resolved. The swiveling funnels of ''Hōshō'' had not proved successful and wind-tunnel testing had not provided an answer. As a result, ''Akagi'' and ''Kaga'' were given different exhaust systems to evaluate in real-world conditions. ''Kaga''{{'}}s funnel gases were collected in a pair of long horizontal ducts which discharged at the rear of each side of the flight deck, in spite of predictions by a number of prominent naval architects that they would not keep the hot gases away from the flight deck. The predictions proved to be correct, not least because ''Kaga'' was slower than ''Akagi'', which allowed the gases to rise and interfere with landing operations. Another drawback was that the heat of the gases made the crew's quarters located on the side of the ship by the funnels almost uninhabitable.<ref name=l34/>

''Kaga'' was completed with four Kawasaki Brown-Curtis geared [[steam turbine]]s with a total of {{convert|91000|shp|kW|lk=on}} on four shafts. As a battleship her expected speed had been {{convert|26.5|kn|lk=in}}, but the reduction in displacement from {{convert|39900|to|33693|LT|MT|0}} allowed this to increase to {{convert|27.5|kn}}, as demonstrated on her [[sea trial]]s on 15 September 1928. She had twelve Kampon Type B (Ro) boilers with a working pressure of {{convert|20|kg/cm2|kPa psi|abbr=on|lk=on}}, although only eight were oil-fired. The other four used a mix of oil and coal. She carried {{convert|8000|LT|MT|0}} of fuel oil and {{convert|1700|LT|MT|0}} of coal to give her a range of {{convert|8000|nmi|lk=in}} at {{convert|14|kn}}.<ref name=l34/>

==Early service and development of carrier doctrine==
{{See also|January 28 Incident}}
[[File:Kaga air ops 1930.jpg|thumb|right|''Kaga'' conducting air operations in 1930. On the upper deck are Mitsubishi B1M torpedo bombers preparing for takeoff. Nakajima A1N Type 3 fighters are parked on the lower deck forward.]]On 1 December 1931 ''Kaga'' was assigned as the flagship of the [[First Carrier Division]] under the command of Rear Admiral [[Takayoshi Katō]].<ref name ="Hata24">Hata, p. 24</ref> The First Carrier Division, along with ''Hōshō'', departed for [[Republic of China (1912–1949)|Chinese]] waters on 29 January 1932 to support [[Imperial Japanese Army]] troops during the [[28 January Incident|Shanghai Incident]] as part of the IJN's [[IJN 3rd Fleet|3rd Fleet]].<ref name=l72/> The B1M3s carried by ''Kaga'' and ''Hōshō'' were the main bombers used during the brief combat over Shanghai.<ref>Peattie, p. 37</ref>

[[File:Ikuta air pt.jpg|thumb|right|Ikuta, Kuroiwa, and Takeo pose in front of a Nakajima A1N2 Type 3]]
''Kaga''{{'}}s aircraft, operating from both the carrier and a temporary base at Kunda Airfield in Shanghai, flew missions in support of Japanese ground forces throughout February 1932. During one of these missions three of ''Kaga''{{'}}s Nakajima A1N2 fighters, including one piloted by future ace [[Toshio Kuroiwa]], escorting three Mitsubishi B1M3 torpedo bombers, scored the IJN's first air-to-air combat victory on 22 February when they shot down a [[Boeing P-12]] flown by an American volunteer pilot.<ref name=Hata24 /><ref>Peattie, pp. 50–51</ref>  ''Kaga'' returned to home waters upon the declaration of the cease-fire on 3 March and resumed fleet training with the rest of the Combined Fleet.<ref name=Hata24 />

At this time, the IJN's developing carrier doctrine was still in its earliest stages. ''Kaga'' and the other carriers were initially given roles as tactical force multipliers supporting the fleet's battleships in the IJN's "[[Kantai Kessen|decisive battle]]" doctrine. In this role, ''Kaga''{{'}}s aircraft were to attack enemy battleships with bombs and torpedoes. Aerial strikes against enemy carriers were later, beginning around 1932–1933, deemed of equal importance in order to establish [[air superiority]] during the initial stages of battle. The essential component in this strategy was that the Japanese carrier aircraft must be able to strike first with a massed aerial attack. As a result, in fleet training exercises the carriers began to operate together in front of or with the main battle line. This revolutionary strategy emphasized maximum speed from both the carriers and the aircraft they carried as well as larger aircraft with greater range. Thus, longer flight decks on the carriers were required in order to handle the newer, heavier aircraft which were entering service.<ref>Peattie, pp. 72–76, 152; Stille, p. 13; Goldstein ([[Jisaburō Ozawa]]), pp. 76–78</ref>

''Kaga'' was soon judged inferior to ''Akagi'' because of her slower speed, smaller flight deck ({{convert|64|ft|m|1}} shorter), and problematic funnel arrangement. Because of ''Kaga''{{'}}s perceived limitations, she was given priority over ''Akagi'' for modernization.<ref>Peattie, pp. 55–56</ref>  ''Kaga'' was relegated to reserve status on 20 October 1933 to begin a second major reconstruction, with an official start date of 25 June 1934.<ref name=l72>Lengerer, p. 172</ref>

==Reconstruction==
During her second reconstruction ''Kaga''{{'}}s two lower flight decks were converted into hangars and, along with the main flight deck, were extended to the bow. This increased the flight deck length to {{convert|248.55|m|ftin|sp=us}} and raised aircraft capacity to 90 (72 operational and 18 in storage).<ref>Peattie, p. 56</ref>  A third elevator forward, {{convert|11.5|x|12|m|ftin|sp=us}}, serviced the extended hangars.<ref name=l9/> Bomb and [[torpedo]] elevators were modified to deliver their munitions directly to the flight deck. Her arrester gear was replaced by a Japanese-designed Type 1 system. A small starboard island superstructure was also installed.<ref name="ireland">Ireland, pp. 102–103</ref>

[[File:Aircraft carrier Kaga sideview IJN.jpg|thumb|upright=1|A rear oblique view of ''Kaga'', {{c.}} 1935]]
Her power plant was completely replaced as were her propellers. ''Kaga'' was equipped with eight improved oil-burning models of the Kampon Type B (Ro) with a working pressure of {{convert|22|kg/cm2|kPa psi|0|abbr=on}} at a temperature of {{convert|300|°C|°F|abbr=on}}. New Kampon multi-stage geared turbines were fitted that increased her power from {{convert|91000|to|127400|shp|kW|abbr=on|0}} during trials. The hull was lengthened by {{convert|10.3|m|ftin|sp=us}} at the stern to reduce drag and she was given another torpedo bulge above the side armor abreast the upper part of the existing bulge to increase her beam and lower her center of gravity as a result of lessons learned from the [[Japanese torpedo boat Tomozuru#The Tomozuru Incident|''Tomozuru'' Incident]] in early 1934. This raised her standard displacement significantly, from {{convert|26900|to|38200|LT|MT|0}}. The extra power and the extra displacement roughly offset each other and her speed increased by less than a knot, up to {{convert|28.34|kn}} on trials. Her fuel storage was increased to {{convert|7500|LT|MT|0}} of [[fuel oil]] which increased her endurance to {{cvt|10000|nmi}} at {{convert|16|kn}}. The lengthy funnel ducting was replaced by a single downturned starboard funnel modeled on that used by the ''Akagi'' with a water-cooling system for the exhaust gasses and a cover that could be raised to allow the exhaust gasses to escape if the ship developed a severe list and the mouth of the funnel touched the sea. The space freed up by the removal of the funnel ducts was divided into two decks and converted into living quarters for the expanded air group.<ref name=l7>Lengerer, p. 137</ref> The carrier's complement increased to 1708 crewmembers.<ref name=tp67>Parshall and Tully, p. 467</ref>

The two twin turrets on the middle flight deck were removed and four new 20&nbsp;cm 3rd Year Type No. 1 guns in casemates were added forward. Her 12&nbsp;cm anti-aircraft guns were replaced by eight {{convert|12.7|cm|adj=on|sp=us}} Type 89 guns in twin mounts. They fired {{convert|23.45|kg|lb|adj=on|sp=us}} projectiles at a rate between 8 and 14 rounds per minute at a muzzle velocity of {{convert|700|-|725|m/s|ft/s|abbr=on}}; at 45°, this provided a maximum range of {{convert|14800|m|yd|sp=us}}, and a maximum ceiling of {{convert|9400|m|ft|sp=us}}.<ref>Campbell, pp. 192–193</ref> Their sponsons were raised one deck to allow them some measure of cross-deck fire. Eleven twin [[Type 96 25 mm AT/AA Gun|25&nbsp;mm Type 96]] gun mounts were added, also on sponsons. They fired {{convert|0.25|kg|lb|adj=on|sp=us}} projectiles at a muzzle velocity of {{convert|900|m/s|ft/s|abbr=on}}; at 50°, this provided a maximum range of {{convert|7500|m|yd|sp=us|0}}, and an effective ceiling of {{convert|5500|m|ft|sp=us}}. The maximum effective rate of fire was only between 110 and 120 rounds per minute due to the frequent need to change the fifteen-round magazines.<ref>Campbell, p. 200</ref> Six {{convert|6.5|mm|adj=on|sp=us}} [[Type 11 Light Machine Gun|Type 11]] machine guns were also carried.<ref name=l7/> Six Type 95 directors were fitted to control the new 25&nbsp;mm guns, but ''Kaga'' retained her outdated Type 91 anti-aircraft directors.<ref name=tp67/>

Several major weaknesses in ''Kaga''{{'}}s design were not rectified. ''Kaga''{{'}}s aviation fuel tanks were incorporated directly into the structure of the carrier, meaning that shocks to the ship, such as those caused by bomb or shell hits, would be transmitted directly to the tanks, resulting in cracks or leaks. Also, the fully enclosed structure of the new hangar decks made fire suppression difficult, at least in part because fuel vapors could accumulate in the hangars. Adding to the danger was the requirement from the Japanese carrier doctrine that aircraft be serviced, fueled, and armed whenever possible on the hangar decks rather than on the flight deck. In addition, the carrier's hangar and flight decks carried little armor protection. Furthermore, there was no redundancy in the ship's fire-extinguishing systems. These weaknesses would later be crucial factors in the loss of the ship.<ref>Peattie, pp. 65, 70, 159; Stille, pp. 15–16; Willmott, p. 415; Parshall and Tully, p. 245</ref>

==Sino-Japanese War==
{{See also|Second Sino-Japanese War}}
''Kaga'' returned to service in 1935 and was assigned to the [[Second Carrier Division]]. The carrier embarked a new set of aircraft, including 16 [[Nakajima A2N]] Type 90 fighters, 16 [[Aichi D1A]] Type 94/96 dive bombers, and 28 [[Mitsubishi B2M]] Type 89 torpedo bombers.<ref>Hata, pp. 24–25</ref>

[[File:Kaga air operations full deck 1937.jpg|thumb|left|''Kaga'' conducts air operations in 1937; on deck are Nakajima A2N, Aichi D1A, and Mitsubishi B2M aircraft]]
The renewal of hostilities with China at the [[Marco Polo Bridge Incident|Marco Polo Bridge]] in July 1937 found ''Kaga'' in home waters. The ship's fighter squadron completed training at [[Ōmura, Nagasaki]] then helped escort ships taking army reinforcements from Japan to China. On 15 August, along with ''Hōshō'' and {{ship|Japanese aircraft carrier|Ryūjō||2}}, the ship took station in the [[East China Sea]] as part of the 3rd Fleet and began supporting Japanese military operations along the central China coast around Shanghai and further inland.<ref>Peattie, pp. 103–104</ref><ref>Hata, p. 25</ref>

''Kaga'' aircraft fought their first battle on 15 August 1937, when thirteen Aichi D1A1 (Type 94) dive-bombers encountered [[Republic of China Air Force|Chinese Air Force]] [[Curtiss A-12 Shrike]] attack-bombers of the [[Development of Chinese Nationalist air force (1937–1945)#Units of the Chinese Airforce 1937–1945|26th and 27th Squadrons]] at Chao'er Airbase preparing for strikes against Japanese positions in Shanghai, and a dogfight duly ensued between the two unlikely dogfighting opponents; two D1A1s were shot down; a third badly shot-up D1A1 returned to ''Kaga'' with a fatally wounded crewman, while the D1A1 flight claimed three Shrikes.<ref>Cheung, p. 15</ref> On 16 August 1937, six Type 90 fighters engaged four Chinese aircraft over [[Jiangwan Airport|Jiangwan]], shooting down three without loss. Between 17 August and 7 September, ''Kaga''{{'}}s Type 90 and two [[Mitsubishi A5M]] Type 96 fighters, which joined the carrier on 22 August, engaged Chinese aircraft on several more occasions.  ''Kaga''{{'}}s fighter pilots claimed to have shot down 10 Chinese aircraft in these encounters without loss.<ref>Hata, pp. 25–26</ref> On 17 August twelve of the carrier's bombers attacked [[Hangzhou]] without fighter escort and 11 of them were shot down by Chinese fighters.<ref>Howarth, p. 213</ref> On 7 September, three Type 96 (A5M) fighters escorted six Type 96 (D1A2) bombers and were engaged by three Chinese [[Curtiss BF2C Goshawk|Hawk IIIs]] near [[Lake Tai|Taihu Lake]]; two Type 96 bombers were quickly shot down, but the ensuing half-hour long dogfight resulted in no further losses for either side despite claims.<ref>{{Cite web|last=Gustavsson|first=Hakans|title=Chinese biplane fighter aces – Lu Ji-Chun|url=http://surfcity.kund.dalnet.se/china_ji-chun.htm|access-date=24 November 2020|website=Biplane Fighter Aces – China|quote=On 7 September three Type 96 (A5M) fighters led by Lt. Igarashi escorted six Type 96 (D1A2) carrier bombers from the Kaga... they were intercepted by a three-aircraft formation of Curtiss Hawk IIIs led by Lt. Lu Ji-chun, Lt. Lai Ming-Tang and Chou Geng-Hsu near Tai Hu. Lu and Chou attacked the bombers and claimed one each... they were then engaged by the A5Ms and tangled with them for half an hour before all breaking off... while Igarashi claimed "three Hawks" and PO1c Handa claiming one, none of the Chinese fighters were actually lost in that engagement.}}</ref> Beginning on 15 September, six Type 90 and six Type 96 fighters, 18 dive bombers, and 18 torpedo bombers were temporarily deployed to Kunda Airfield from the ship to support land operations.<ref name="Hata26">Hata, p. 26</ref>

[[File:Kaga China Incident.jpg|thumb|An D1A2 dive bomber flies near ''Kaga'' during the China incident]]
On 26 September the carrier went to [[Sasebo, Nagasaki|Sasebo]] for reprovisioning. At Sasebo, the carrier received new replacement aircraft including 32 [[Yokosuka B4Y]] Type 96 carrier attack planes (torpedo bombers), 16 [[Aichi D1A2]] Type 96 carrier bombers (dive bombers), and 16 more Type 96 fighters. Several [[Nakajima A4N]] Type 95 fighter aircraft augmented the carrier's fighter group at an unspecified later date.<ref name = "Hata26" />

''Kaga'' returned to the front in early October 1937, and except for two brief trips to Sasebo, remained off China until December 1938. Using [[Taiwan]] (then part of the [[Empire of Japan]]) as its base, the carrier steamed {{convert|29048|nmi}} supporting military operations from the [[South China Sea|South]] and East China Seas. During that time, ''Kaga'' bombers supported army operations by attacking enemy railroad bridges, airfields, and transportation vehicles. The carrier's fighter pilots claimed to have destroyed at least 17 Chinese aircraft in aerial combat while losing five aircraft themselves. On 12 December 1937 ''Kaga'' aircraft participated in the [[Panay incident]].<ref>Hata, pp. 26–27; Werneth, p. 160; Toland, p. 49</ref>

On 11 November 1937, three Chinese Air Force [[Northrop Gamma|Northrop Gamma 2ECs]] of the [[Development of Chinese Nationalist air force (1937–1945)|2nd BG, 14th Squadron]] led by Captain Yu Y.C. attacked ''Kaga'' off the Maanshan Islands near Shanghai; the bombs fell wide into ''Kaga''{{'}}s wake, and the Chinese Gammas were pursued and intercepted by three A5Ms of ''Kaga''{{'}}s [[combat air patrol]] (CAP) led by flight leader [[Jirō Chōno]], which shot down two of the Gammas, while Yu managed to escape into the clouds and return to base in his damaged Gamma.<ref>{{cite web |last1=Gustavsson |first1=Håkan |title=Lieutenant (junior grade) Hatsu-o Hidaka |url=http://surfcity.kund.dalnet.se/japan_hidaka.htm |website=Biplane Fighter Aces from the Second World War |access-date=8 November 2020}}</ref>

Six ''Kaga'' fighters were assigned to land bases near Shanghai and Nanking between 9 December 1937 and 15 January 1938. Nine fighters were temporarily based out of Nanking from 3 March through 4 April 1938. On 13 April 1938, ''Kaga'' launched eighteen D1A1s and three each of A4Ns and A5Ms on a strike against [[Guangzhou|Canton]], and they were met by two squadrons of [[Gloster Gladiator]]s of the 5th Fighter Group led by Captain [[John Huang Xinrui|John Xinrui Huang]] and Captain [[Louie Yim-qun]]; Huang would score a triple kill in this battle against the ''Kaga'' raid, while Jirō Chōno (A5M) and [[Hatsuo Hidaka]] (A4N) would each claim double kills, including Chōno's shooting-down of Huang, who was injured bailing out.<ref>Cheung, p. 65</ref> ''Kaga''{{'}}s fighter group at this time included future aces Jirō Chōno, [[Osamu Kudō]], [[Yoshio Fukui]], [[Watari Handa]], [[Masaichi Kondō]], Hatsuo Hidaka, [[Kiichi Oda]], [[Satoru Ono]], and [[Chitoshi Isozaki]].<ref>Hata, pp. 28, 322, 346, 353, 361, 366, 368</ref> The US Navy decrypted an IJN message which reportedly indicated that the attack on the {{USS|Panay|PR-5|2}} and other neutral ships in the [[Yangtze River]] had been knowingly and deliberately planned by an air officer on ''Kaga''.<ref>Toland, p. 49</ref>

''Kaga'' entered the shipyard on 15 December 1938, where her arresting gear was replaced by a Type 3 system and her bridge was modernized. The flight deck and hangar areas were enlarged, increasing the carrier's aircraft capacity. The ship was completely overhauled from 15 November 1939 to 15 November 1940 before returning to active service. In the meantime, a new generation of aircraft had entered service and ''Kaga'' embarked 12 A5M fighters, 24 D1A dive bombers and 36 B4Y torpedo bombers. Another 18 aircraft were carried in crates as spares.<ref name=l72/><ref>Hata, p. 27</ref><ref group=Note>Hata, p. 27, gives ''Kaga''{{'}}s aircraft complement after overhaul as 12 fighters with four spares, 18 dive bombers with six spares, and 48 torpedo bombers with 16 spares.</ref>

The Japanese carriers' experiences off China had helped further develop the IJN's carrier doctrine. One lesson learned in China was the importance of concentration and mass in projecting naval air power ashore. Therefore, in April 1941 the IJN formed the [[1st Air Fleet of the Imperial Japanese Navy|First Air Fleet]] to combine all of its fleet carriers under a single command. On 10 April 1941 ''Kaga'' was assigned to the First Carrier Division with ''Akagi'' as part of the new carrier fleet, which also included the Second and [[Fifth Carrier Division|Fifth]] carrier divisions. The IJN centered its doctrine on airstrikes that combined the air groups within carrier divisions, rather than each individual carrier. When more than one carrier division was operating together, the divisions' air groups were combined with each other.  This doctrine of combined, massed, carrier air attack groups was the most advanced of its kind of all the world's navies.  The IJN, however, remained concerned that concentrating all of its carriers together would render them vulnerable to being wiped out all at once by a massive enemy air or surface strike. Thus, the IJN developed a compromise solution in which the fleet carriers would operate closely together within their carrier divisions but the divisions themselves would operate in loose rectangular formations, with approximately {{convert|7000|m|yd}} separating the carriers from each other.<ref>Parshall and Tully, pp. 82, 86, 137–138, and 416; Peattie, pp. 124–125, 147–153; Tully; Stille, pp. 13–14</ref><ref group=Note>According to Parshall and Tully, pp. 86–87, the Japanese would not usually launch their entire carrier air groups into a single massed attack. Instead, each carrier would launch a "deckload strike" of all its aircraft that could be spotted at one time on each flight deck. Subsequent attack waves consisted of the next deckload of aircraft. Thus, 1st Air Fleet air attacks would often consist of at least two, massed waves of aircraft. Peattie (p. 152) and [[Jisaburō Ozawa]] (Goldstein, pp. 78–80) emphasize that the First Air Fleet was ''not'' the IJN's primary strategic striking force. The IJN still considered the First Air Fleet an integral component in the Combined Fleet's decisive battle task force centered on battleships.</ref>

Although the concentration of so many fleet carriers into a single unit was a new and revolutionary offensive strategic concept, the First Air Fleet suffered from several defensive deficiencies which gave it, in [[Mark Peattie]]'s words, a {{" '}}[[wikt:glass jaw|glass jaw]]':  it could throw a punch but couldn't take one."<ref>Peattie, p. 159</ref> Japanese carrier anti-aircraft guns and associated fire control systems had several design and configuration deficiencies which limited their effectiveness. The IJN's fleet CAP consisted of too few fighter aircraft and was hampered by an inadequate early warning system, including a lack of [[radar]]. Poor radio communications with the fighter aircraft inhibited effective command and control of the CAP. The carriers' escorting warships were deployed as visual scouts in a ring at long range, not as close anti-aircraft escorts, as they lacked training, doctrine, and sufficient anti-aircraft guns. These deficiencies would eventually doom ''Kaga'' and other First Air Fleet carriers.<ref>Parshall and Tully, pp. 85 and 136–145; Peattie, pp. 155–159; Stille, pp. 14–15, 50–51</ref>

==World War II==
===Pearl Harbor===
{{Further|Attack on Pearl Harbor}}
{{Multiple image|total_width=380|align= right
|image1=Kaga Pearl Harbor brief.jpg
|alt1=
|image2=Kaga and Zuikaku Pearl Harbor.jpg
|alt2=
|footer=Left: Lieutenant Ichirō Kitajima briefs his B5N crews on the carrier deck about the attack plan the day before the raid on Pearl Harbor. Right: ''Kaga'' (foreground), with [[Japanese aircraft carrier Zuikaku|''Zuikaku'']] (background), heads towards Pearl Harbor sometime between 26 November and 7 December 1941.
}}

In November 1941 the IJN's Combined Fleet, under [[Isoroku Yamamoto]], prepared to participate in Japan's initiation of a formal war with the United States by conducting a preemptive strike against the [[United States Navy]]'s [[United States Pacific Fleet|Pacific Fleet]] base at [[Pearl Harbor]], Hawaii. On 17 November ''Kaga'', under the command of Captain [[Jisaku Okada]] loaded 100 torpedoes at Saeki Bay, Hiroshima; these torpedoes were specially designed for use in the shallow waters of the Pearl Harbor anchorage. On 19 November, ''Kaga'' and the rest of the Combined Fleet's mobile strike force ([[1st Air Fleet of the Imperial Japanese Navy#Kido Butai|''Kido Butai'']]), under [[Chuichi Nagumo]] and including six fleet carriers from the First, Second, and Fifth Carrier Divisions, assembled in Hitokappu Bay at [[Etorofu Island]]. The fleet departed Etorofu on 26 November and followed a course across the north-central Pacific to avoid commercial shipping lanes.<ref name="Tully">Tully</ref>

For the attack on Pearl Harbor, ''Kaga'' carried a total of 18 [[Mitsubishi A6M Zero]] [[Fighter aircraft|fighters]], 27 [[Nakajima B5N]] torpedo bombers and 27 [[Aichi D3A]]<ref group=Note>The [[World War II Allied names for Japanese aircraft|Allied reporting name]] for these aircraft were "Zeke", "Kate" and "Val" respectively.</ref> dive bombers, plus three crated aircraft of each type for the operation. During the morning of 7 December 1941 ''Kaga'' aircraft participated in both First Air Fleet strikes launched against [[Oahu]] from a position {{convert|230|nmi|km|-1}} north of the island. In the first strike of 183 total aircraft (six aborted), 26 ''Kaga'' B5N carrier attack bombers attacked the American ships at anchor with bombs and torpedoes, escorted by nine Zeros. In the second strike of 167 aircraft (four aborted), 26 ''Kaga'' D3A dive bombers targeted the airfield at [[Ford Island]] in the middle of the harbor while nine Zeros provided escort and attacked aircraft on the ground.<ref>Zim, p. 153</ref> A total of five B5Ns, four Zeros and six D3As from the ship were lost during the two strikes, along with their aircrews, a total of 31 personnel.<ref>Lengerer, p. 174; Stille, p. 19; Werneth, p. 111; Evans and Fuchida, p. 54</ref> ''Kaga''{{'}}s bomber and torpedo crews claimed hits on the battleships {{USS|Nevada|BB-36|2}}, {{USS|Oklahoma|BB-37|2}}, {{USS|Arizona|BB-39|2}}, {{USS|California|BB-44|2}}, {{USS|West Virginia|BB-48|2}}, and {{USS|Maryland|BB-46|2}}.<ref>Lengerer, p. 175</ref> The ship's fighter pilots claimed to have shot down one US aircraft and destroyed 20 on the ground.<ref name="Hata, p. 28">Hata, p. 28</ref><ref group=Note>Fourteen of the B5N in the first wave carried bombs and the other 12 torpedoes. A 15th bomb-carrying B5N aborted due to engine trouble. Five torpedo planes and two Zeros were lost in the first wave and two Zeros and the six dive bombers in the second wave (Werneth, p. 111).</ref> Upon completion of the attack, the First and Fifth Carrier divisions, including ''Kaga'', returned immediately to Japan.<ref name="Tully"/>

===Pacific conquest===
{{See also|Pacific War}}
In January 1942, together with the rest of the First and Fifth Carrier Division carriers and staging out of [[Chuuk Lagoon|Truk]] (now Chuuk) in Micronesia, ''Kaga'' supported the [[battle of Rabaul (1942)|invasion of Rabaul]] in the [[Bismarck Islands]]. ''Kaga'' provided 27 bomb-carrying B5N and 9 Zeros for the initial airstrike on [[Rabaul]] on 20 January 1942, during which one B5N was shot down by anti-aircraft fire. The First Carrier Division attacked Allied positions at nearby [[Kavieng]] the following day, of which ''Kaga'' contributed nine Zeros and sixteen D3As. On the 22nd ''Kaga''{{'}}s D3As and Zeros again attacked Rabaul and two dive bombers had to make emergency landings, but the crews were rescued. ''Kaga'' returned to Truk on 25 January and Rabaul and Kavieng were successfully occupied by Japanese forces by February.<ref>Lengerer, pp. 175–176; Werneth, p. 140</ref>

On 9 February ''Kaga'' hit a reef at [[Palau]] after she had unsuccessfully sortied against American carrier forces [[Marshalls-Gilberts raids|attacking]] the [[Marshall Islands]] on 1 February. The damage reduced the carrier's speed to 18 knots.<ref name="Tully"/><ref group=Note>Takeshi Maeda, a B5N crewmember on ''Kaga'', states that the carrier grounded at Staring Bay in March, not at Palau in February. The discrepancy is not explained in the sources. (Werneth, p. 116)</ref>  After temporary repairs, she continued to the [[Timor Sea]], where on 19 February 1942 she, with the other carriers of the First and Second Carrier Divisions, launched [[Bombing of Darwin|air strikes]] against [[Darwin, Northern Territory|Darwin]], Australia, from a point {{convert|100|nmi|km|-1}} southeast of the easternmost tip of [[Timor]]. ''Kaga'' contributed 27 B5Ns (carrying bombs), 18 D3A, and 9 Zeros to the attack, which caught the defenders by surprise. Eight ships were sunk, including the [[destroyer]] {{USS|Peary|DD-226|2}}, and fourteen more were damaged, at a cost of only one of ''Kaga''{{'}}s B5Ns. In March 1942, ''Kaga'', based out of [[Staring-baai]], helped cover the invasion of [[Java (island)|Java]], although her only contribution appears to have been aircraft for the 5 March 1942 airstrike on [[Cilacap Regency|Tjilatjap]]. In that attack ''Kaga'' contributed 27 bomb-carrying B5N escorted by nine Zeros. The attacking aircraft bombed merchant ships in the harbor, sinking eight of them, and attacked anti-aircraft batteries and a warehouse without loss. Most of the Allied forces in the Dutch East Indies surrendered to the Japanese later in March.  ''Kaga'' was unable to participate in the [[Indian Ocean raid]] in April because of the damage she had received in February. Instead, she sailed for Sasebo on 15 March for repairs, entering [[drydock]] on 27 March. The repairs were completed on 4 May.<ref>Lengerer, pp. 176–177, 305–307; Tully; Werneth, p. 140; Gill, p. 590</ref><ref group=Note>While ''Kaga'' was in drydock on 18 April 12 Zeros from the carrier's air group based at [[Kisarazu Air Field]] participated in the failed counterattack against the US carriers which had launched the [[Doolittle raid]] bombers. The attack group, including 29 land bombers and 12 Zeros from the [[26th Air Flotilla]] in addition to the ''Kaga'' fighters, flew east for {{cvt|600|nmi}} before turning back after being unable to locate the American carriers, which had already departed the area (Hata, p. 148). After the Indian Ocean raid, ''Kaga'' was used for limited air operations training by all the First Air Fleet air units in May as the other carriers were in the shipyard for refitting. (Parshall and Tully, p. 88)</ref>

===Battle of Midway===
{{Further|Battle of Midway}}

====Midway raid====
Concerned by the US carrier strikes such as the [[Doolittle Raid]], on the Marshall Islands, and the [[Invasion of Lae-Salamaua|Lae-Salamaua]] raids, Yamamoto was determined to force the US Navy into a showdown to eliminate the American carrier threat. Yamamoto decided to invade and occupy [[Midway Island]], which he was sure would draw out the American carrier forces to battle. The Midway invasion was codenamed by the Japanese as Operation MI.<ref>Stille, p. 22</ref>

In support of ''MI'', on 27 May 1942, ''Kaga'' departed the [[Seto Inland Sea|Inland Sea]] with the Combined Fleet on her final mission, in the company of carriers ''Akagi'', {{ship|Japanese aircraft carrier|Hiryū||2}}, and {{ship|Japanese aircraft carrier|Sōryū||2}} which constituted the First and Second Carrier Divisions. Her aircraft complement was 27 Zeros, 20 D3As, and 27 B5Ns.<ref>Parshall and Tully, pp. 450–451</ref><ref group=Note>Nine of the Zeros were intended to be stationed on Midway after the invasion and belonged to the 6th Air Group. Two of the D3As were in crates and were either replacements for ''Sōryū'' or also members of the 6th Air Group. (Parshall and Tully, p. 451)</ref> With the fleet positioned {{convert|250|nmi|abbr=on}} northwest of Midway Island at dawn on 4 June 1942, ''Kaga'' contributed eighteen D3As, commanded by Lieutenant Shōichi Ogawa, escorted by nine Zeros to the strike against the island. The carrier's B5Ns were armed with torpedoes and kept ready in case enemy ships were discovered during the Midway raid. One each of the D3As and Zeros was shot down by AA fire over Midway, and another four D3As were damaged. ''Kaga''{{'}}s Zero pilots claimed to have shot down 12 US aircraft over Midway Island. One ''Kaga'' B5N was launched to augment the fleet's reconnaissance of the surrounding ocean.<ref group=Note>Twenty-five total US aircraft were lost over Midway during the air raid. (Willmott, p. 380)</ref> The carrier also put up two Zeros on CAP.<ref name="Hata, p. 28"/><ref>Parshall and Tully, pp. 126, 515; Evans and Fuchida, p. 138; Lundstrom, pp. 330–331</ref>  Another five Zeros reinforced her CAP at 07:00 and the seven fighters helped to defend the Kido Butai from the first US air attackers from Midway Island at 07:10. Unknown to the Japanese, the US Navy had divined the Japanese ''MI'' plan from [[signals intelligence]] and had prepared an ambush using its three available carriers, positioned northeast of Midway.<ref>Parshall and Tully, pp. 151, 154; Stille, p. 59</ref>

At 07:15 [[Chūichi Nagumo|Admiral Nagumo]] ordered the B5Ns still on ''Kaga'' and ''Akagi'' rearmed with bombs for another attack on Midway itself. This process was limited by the number of ordnance carts used to handle the bombs and torpedoes and the limited number of ordnance elevators. Thus, the torpedoes could not be struck below until after all the bombs were moved up from their [[magazine (artillery)|magazine]], assembled and mounted on the aircraft. This process normally took about an hour and a half; more time would be required to bring the aircraft up to the flight deck and warm up and launch the strike group. Around 07:40 Nagumo reversed his order when he received a message that American carriers had been spotted. At 07:30 ''Kaga'' recovered three of her CAP.<ref name=p8>Parshall and Tully, pp. 156–159, 508</ref>

====Sinking====
''Kaga''{{'}}s four remaining CAP fighters were in the process of landing when 16 [[United States Marine Corps|Marine]] [[SBD Dauntless]] dive-bombers from Midway, led by [[Lofton R. Henderson]], attacked [[Japanese aircraft carrier Hiryu|''Hiryu'']] around 07:55 without result.<ref>Parshall and Tully, p. 180</ref> Five Zeros were launched at 08:15 and three intercepted a dozen Midway-based [[United States Army]] [[B-17 Flying Fortress]]es attempting to bomb the three other carriers from {{convert|20000|ft}}, but only limited damage was inflicted on the heavy bombers, although their attacks all missed. Five D3As also joined the CAP around this time. Another trio of Zeros were launched at 08:30. ''Kaga'' began landing her returning Midway strike force aboard around 08:35 and was finished by 08:50; one Zero pilot died after crash-landing his aircraft.<ref>Parshall and Tully, pp. 196, 199</ref>

The five Zeros launched at 08:15 were recovered aboard at 09:10 and replaced by six more Zeros launched at 09:20. They intercepted the first US carrier aircraft to attack, [[TBD Devastator]] torpedo-bombers of [[VT-8]] from the US carrier {{USS|Hornet|CV-8|2}} at 09:22, and shot down all 15, leaving only a single survivor, [[George H. Gay, Jr.]], treading water. Shortly thereafter, 14 Devastators from [[Torpedo Squadron 6|VT-6]] from the US carrier {{USS|Enterprise|CV-6|2}}, led by [[Eugene E. Lindsey]], were spotted. They tried to sandwich ''Kaga'', but the CAP, reinforced by another six Zeros launched by ''Kaga'' at 10:00, shot down all but four of the Devastators, and the carrier dodged the torpedoes.<ref>Parshall and Tully, pp. 213–214; Stille, p. 62</ref>

Soon after the torpedo plane attacks, American carrier dive bombers arrived over the Japanese carriers almost undetected and began their dives. At 10:22, 25 SBD Dauntless dive-bombers from ''Enterprise'', led by [[C. Wade McClusky]], hit ''Kaga'' with one {{convert|1000|lb|adj=on}} bomb and at least three {{convert|500|lb|adj=on}} bombs. The first landed near her rear elevator and set the berthing compartments on fire, and the next bomb hit the forward elevator and penetrated the upper hangar, setting off explosions and fires among the armed and fueled planes on her hangar deck. The third bomb exploded directly on the island, destroying the bridge, killing Okada and most of his command staff. The 1000-pound bomb hit amidships and penetrated the flight deck to explode on the upper hangar. The explosions ruptured the ship's [[avgas]] lines, damaged both her port and starboard fire mains and the emergency generator powering her fire pumps, as well as knocking out the [[carbon dioxide]] fire suppression system.<ref>Parshall and Tully, pp. 228, 234–236, 248–250; Stille, pp. 62–63</ref> Fueled by the avgas pouring onto the hangar deck, the fires detonated the {{convert|80000|lb|kg}} of bombs and torpedoes strewn across the hangar deck in a series of catastrophic multiple fuel-air explosions that blew out the hangar sides.<ref>Parshall and Tully, pp. 255–256; Willmott, pp. 426–427</ref> At nearly the same time, dive bombers hit and fatally damaged ''Akagi'' and ''Sōryū''.<ref>Stille, p. 63</ref><ref group=Note>{{USS|Nautilus|SS-168|6}} fired four torpedoes at the carrier; one misfired, two others missed, and one hit the burning ''Kaga'' around 14:05, but it was a [[dud]]. (Parshall and Tully, pp. 302–303) The torpedo broke in two and the warhead portion sank. The floating half was later used as a life preserver by several ''Kaga'' survivors. (Willmott, p. 427)</ref>

Unable to contain her fires, ''Kaga''{{'s}} survivors were taken off by the destroyers {{ship|Japanese destroyer|Hagikaze||2}} and {{ship|Japanese destroyer|Maikaze||2}} between 14:00 and 17:00.<ref group=Note>Parshall and Tully (p. 337) state that the two destroyers rescued over 700 of the carrier's crew. Since the carrier reportedly had a complement of 1708 (Parshall and Tully, p. 467), there should have been around 900 survivors, but the discrepancy in the numbers is not explained by the sources.</ref> Around 19:25 she was scuttled by two torpedoes from ''Hagikaze'' and sank stern-first at position {{coord|30|23|N|179|17|W|display=inline,title}}.<ref>Parshall and Tully, p. 338; Tully; Werneth, p. 142</ref> [[Warrant Officer]] Takeshi Maeda, an injured ''Kaga'' B5N aircrew member rescued by ''Hagikaze'', described the scene: "My comrade carried me up to the deck so I could see the last moments of our beloved carrier, which was nearby. Even though I was in pain tears started to run down my cheeks, and everyone around me was crying; it was a very sad sight."<ref>Werneth, p. 121</ref>

The carrier's crew suffered 811 fatalities, mainly among the aircraft mechanics and armorers stationed on the hangar decks and the ship's engineers, many of whom were trapped below in the boiler and engine rooms by uncontrolled fires raging on the decks above them. Twenty-one of the ship's aviators were killed.<ref>Parshall and Tully, p. 476</ref><ref group=Note>Peattie, p. 338, states that eight ''Kaga'' airmen were killed in the air and 13 died aboard the ship. Of the 15 ''Kaga'' CAP Zeros airborne at the time the carrier was hit, five were destroyed in aerial combat and the remainder were recovered by ''Hiryū''. Two subsequently participated in the second ''Hiryū'' airstrike on ''[[USS Yorktown (CV-5)|Yorktown]]'' while four others augmented the remaining carrier's CAP. All 10 pilots survived (Parshall and Tully, pp. 502–503; Lundstrom, pp. 351, 414).</ref> ''Kaga''{{'}}s surviving crewmembers were restricted incommunicado to an airbase in Kyūshū for one to two months after returning to Japan, to help conceal word of the Midway defeat from the Japanese public.<ref>Werneth, p. 156</ref> Many of the survivors were then transferred back to frontline units without being allowed to contact family. Some of the injured were quarantined in hospitals for almost a year.<ref>Parshall and Tully, pp. 386–387</ref> This was the highest loss of lives of all the Japanese carriers lost at Midway.

The loss of ''Kaga'' and the three other IJN carriers at Midway (''Hiryū'' was also sunk during the battle), with their aircraft and veteran pilots, was a crucial strategic defeat for Japan and contributed significantly to Japan's ultimate defeat in the war.<ref>Fuchida and Okumiya, p. 231</ref>

==Wreck survey==
In May 1999, the Nauticos Corporation, in partnership with the US Navy, discovered some wreckage from ''Kaga''.<ref>{{cite web|url=http://www.nauticos.com/midway/IJNwreckanalysis-kaga.htm |title=IJN Carrier Wreckage- Identification Analysis |publisher=Nauticos Corporation |access-date=2 May 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110305092121/http://www.nauticos.com/midway/IJNwreckanalysis-kaga.htm |archive-date= 5 March 2011 }}</ref> They employed the research vessel {{ship|RV|Melville||2}} during a survey of a fleet exercise area with the US Navy's recently modified SEAMAP acoustic imaging system. A follow-on search by {{ship|USNS|Sumner|T-AGS-61|6}} in September 1999 located the wreckage and took photos of it.<ref>{{cite web|url=http://www.nauticos.com/press/10-29-99.htm |title=Navy and Industry Collaborate for Historical Find |date=20 February 2001 |publisher=Nauticos Corporation |access-date=21 May 2010 |url-status=dead |archive-url=https://web.archive.org/web/20101215172540/http://www.nauticos.com/press/10-29-99.htm |archive-date=15 December 2010 }}</ref> The wreckage included a {{convert|50|foot|adj=on}} long section of hangar bulkhead, two 25&nbsp;mm anti-aircraft gun tubs, and a landing light array. The artifacts were at a depth of {{convert|17000|ft|m}}.<ref>Parshall and Tully, pp. 491–493</ref>

On 18 October 2019, the wreck of ''Kaga'' was located by the Director of Undersea Operations for [[Vulcan Inc.]] Rob Kraft, [[David W. Jourdan]] and [[Naval History and Heritage Command]] historian Frank Thompson aboard {{RV|Petrel}}. She sits upright at a depth of about {{cvt|5.4|km|ft|order=flip}}, buried up to the degaussing wires in the seafloor and with most of her superstructure and flight deck missing. The wreck is surrounded by a large debris field and has been heavily colonized by marine growth.<ref>{{cite web|url=https://www.independent.co.uk/news/world/americas/rv-petrel-battle-midway-kaga-wreck-aircraft-carrier-ww2-paul-allen-a9161481.html|title=Deep-sea Explorers Find Wreck of Japanese Second World War Aircraft Carrier Sunk in Pivotal Battle of Midway|last=Sharman|first=Jon|date=18 October 2019|access-date=18 October 2019|newspaper=The Independent}}</ref> The wreck of ''Akagi'' was found by the same crew two days later.<ref>{{Cite news|url=https://www.theguardian.com/world/2019/oct/21/humbling-wreckage-of-japanese-ships-from-battle-of-midway-found-in-pacific|title='Humbling' Wreckage of Japanese Ships From Battle of Midway Found in Pacific|last=Beaumont|first=Peter|date=21 October 2019|work=The Guardian|access-date=21 October 2019|issn=0261-3077}}</ref> A more extensive survey of the wreck was conducted by the [[EV Nautilus]] in September 2023.<ref>Rousselle, Christine, "[https://www.foxnews.com/lifestyle/undersea-video-lost-wwii-aircraft-carriers-provides-clues-last-moments Undersea video of lost WWII aircraft carriers provides new clues about their dramatic last moments]", ''[[Fox News]]'', 7 October 2023</ref>

==Notes==
{{Reflist|group=Note}}

==Footnotes==
{{Reflist|25em}}

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 |first=G. Hermon
 |year=1957
 |url=http://www.awm.gov.au/histories/second_world_war/volume.asp?levelID=67910
 |title=Volume I – Royal Australian Navy, 1939–1942
 |series=''[[Australia in the War of 1939–1945]]'', Series 2: Navy
 |location=Canberra
 |publisher=[[Australian War Memorial]]
 |url-status=dead
 |archive-url=https://web.archive.org/web/20090525001721/http://www.awm.gov.au/histories/second_world_war/volume.asp?levelID=67910
 |archive-date=25 May 2009
|edition=1st
 }}
* {{cite book
 | editor1-last = Goldstein
 | editor1-first = Donald M.
 | editor2-first = Katherine V. | editor2-last = Dillon
 | year = 2004
 | title = The Pacific War Papers: Japanese Documents of World War II
 | publisher=Potomac Books
 | location = [[Dulles, Virginia|Dulles]], Virginia
 | isbn = 1-57488-632-0
}}
* {{cite book
 | last = Hata
 | first = Ikuhiko
 | author-link = Ikuhiko Hata
 | author2 = Izawa, Yasuho
 | others = Translated by Don Cyril Gorham
 | orig-year = 1975
 | year = 1989
 | title = Japanese Naval Aces and Fighter Units in World War II
 | publisher = Naval Institute Press
 | location = [[Annapolis, Maryland|Annapolis]], Maryland
 | isbn = 0-87021-315-6
 | url = https://archive.org/details/japanesenavalace00hata
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* {{cite book
 | last = Howarth
 | first = Stephen
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 | title = The Fighting Ships of the Rising Sun: The Drama of the Imperial Japanese Navy 1895–1945
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}}
* {{cite book |title=Aircraft Carriers of the World |last=Ireland |first=Bernard |year=2007 |publisher=Southwater |location=London |isbn=978-1-84476-363-4 |url-access=registration |url=https://archive.org/details/aircraftcarriers0000irel }}
* {{cite book
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 | year = 1977
 | title = Warships of the Imperial Japanese Navy, 1869–1945
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 | location = [[Annapolis, Maryland|Annapolis]], Maryland
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* {{cite book|last=Lengerer|first=Hans|year=1982|chapter=Akagi & Kaga|title=Warship VI|publisher=Conway Maritime Press|location=London|isbn=0-87021-981-2|editor=Roberts, John}}
* {{cite book
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* {{cite book | last1=Parshall | first1=Jonathan | last2=Tully | first2=Anthony | year=2005 | title=Shattered Sword: The Untold Story of the Battle of Midway | publisher=Potomac Books | location=Dulles, Virginia | isbn=1-57488-923-0 | url=https://archive.org/details/shatteredswordun0000pars }}
* {{cite book|last=Peattie|first=Mark|author-link=Mark Peattie|title=Sunburst: The Rise of Japanese Naval Air Power 1909–1941|year=2001|publisher=Naval Institute Press|location=Annapolis, Maryland |isbn=1-55750-432-6}}
* {{cite book
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* {{cite book
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}}
* {{cite book
 | last = Toland
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 | year = 2003 | orig-year = 1970
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 | publisher=The Modern Library
 | location = New York
 | isbn = 0-8129-6858-1
}}
* {{cite web
| last = Tully
| first = Anthony P.
| year = 2000
| url = http://www.combinedfleet.com/kaga.htm
| title = IJN Kaga: Tabular Record of Movement
| work=Kido Butai
| publisher=Combinedfleet.com
| access-date =15 June 2010
}}
* {{cite web
 |last=Nauticos LLC
 |year=1999
 |url=http://www.nauticos.com/midway/IJNwreckanalysis-exec.htm
 |title=IJN Carrier Wreckage- Identification Analysis
 |publisher=nauticos.com
 |access-date=6 June 2013
|url-status=dead
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 |archive-date=17 August 2013
}}
* {{cite book
 | last = Werneth
 | first = Ron
 | year = 2008
 | title = Beyond Pearl Harbor: The Untold Stories of Japan's Naval Airmen
 | publisher=Schiffer Military History
 | location = Atglen, Pennsylvania
 | isbn = 978-0-7643-2932-6
}}
* {{cite book
 | last = Willmott
 | first = H. P.
 | year = 1983
 | title = The Barrier and the Javelin: Japanese and Allied Pacific Strategies, February to June 1942
 | url = https://archive.org/details/barrierjavelin00hpwi
 | url-access = registration
 | publisher=Naval Institute Press
 | location = [[Annapolis, Maryland|Annapolis]], Maryland
 | isbn = 978-1-59114-949-1
}}
* {{cite book|last=Zimm|first=Alan D.|title=Attack on Pearl Harbor: Strategy, Combat, Myths, Deceptions|year=2011|publisher=Casemate Publishers|location=Havertown, Pennsylvania|isbn=978-1-61200-010-7}}

==Further reading==
* {{cite journal |last1=Worth |first1=Richard.|title=Question 13/46: Catapults on WW II Japanese Aircraft Carriers |journal=Warship International |year=2010 |volume=XLVII |issue=2 |pages=102–03 |issn=0043-0374}}

==External links==
{{Commons category|Kaga (ship, 1928)|Kaga}}
* [http://ww2db.com/ship_spec.php?ship_id=9 Kaga], World War II Database

{{Tosa class battleships}}
{{WWII Japanese ships}}
{{Pearl Harbor attack}}
{{June 1942 shipwrecks}}
{{featured article}}

{{DEFAULTSORT:Kaga}}
[[Category:Tosa-class battleships]]
[[Category:Ships built by Kawasaki Heavy Industries]]
[[Category:Ships built by Yokosuka Naval Arsenal]]
[[Category:1921 ships]]
[[Category:Aircraft carriers of the Imperial Japanese Navy]]
[[Category:Second Sino-Japanese War naval ships of Japan]]
[[Category:World War II aircraft carriers of Japan]]
[[Category:Attack on Pearl Harbor]]
[[Category:Ships of the Battle of Midway]]
[[Category:Aircraft carrier fires]]
[[Category:Scuttled vessels]]
[[Category:World War II shipwrecks in the Pacific Ocean]]
[[Category:Maritime incidents in June 1942]]
[[Category:1999 archaeological discoveries]]
[[Category:2019 archaeological discoveries]]
[[Category:Shipwreck discoveries by Paul Allen]]