May 5: Ascension Day in Western Christianity (2005); Liberation Day in Denmark, Ethiopia, and the Netherlands; Children's Day in Japan and South Korea.
- 1862 - Cinco de Mayo in Mexico: Troops led by Ignacio Zaragoza halted a French invasion in the Battle of Puebla.
- 1864 - American Civil War: Ulysses S. Grant's Overland Campaign began with the Battle of the Wilderness.
- 1904 - Cy Young of the Boston Americans pitched the first perfect game in the modern era of baseball.
- 1949 - The Council of Europe was formed.
- 1950 - Prince Bhumibol Adulyadej was crowned in Bangkok as King Rama IX of Thailand, currently the world's longest-serving head of state.