June 5: UN World Environment Day
- 1849 - Denmark became a constitutional monarchy.
- 1947 - George Marshall called for economic aid to war-torn Europe.
- 1967 - The Six-Day War began with an Israeli Air Force attack on Egypt, Jordan, and Syria.
- 1968 - Sirhan Sirhan mortally shot Robert F. Kennedy in Los Angeles.
- 1995 - A new phase of matter, the Bose-Einstein condensate was discovered.
- 2004 - U.S. President Ronald Reagan died.