May 5: Buddha's Birthday in Macau, Hong Kong, Taiwan and South Korea (2006); Liberation Day in Denmark, Ethiopia, and the Netherlands; Children's Day in Japan and South Korea.
- 1789 - French Revolution: The Estates-General convened in Versailles to discuss a financial crisis in France.
- 1862 - Cinco de Mayo in Mexico: Troops led by Ignacio Zaragoza halted a French invasion in the Battle of Puebla.
- 1904 - Cy Young (pictured) 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.