1. 1500 – Portuguese explorer Pedro Álvares Cabral officially discovered Brazil, claiming the land for Portugal.

2. 1529 – The Treaty of Zaragoza was signed by Spain and Portugal, defining their respective spheres of influence in the Asia-Pacific region, particularly regarding the Moluccas (Spice Islands).

3. 1864 – The U.S. Congress passed the Coinage Act, which mandated the inscription “In God We Trust” on all coins minted as United States currency.

4. 1889 – The Oklahoma Land Rush began at noon, as thousands of settlers raced to claim land in the “Unassigned Lands” of the Oklahoma territory.

5. 1915 – The use of poison gas in warfare became a grim reality when chlorine gas was used by German troops in the Second Battle of Ypres during World War I.

6. 1970 – The first Earth Day was celebrated in the United States, founded by Senator Gaylord Nelson to promote ecology and raise awareness of environmental issues.

7. 1993 – The British National Science and Engineering Week observance concluded with a debate on the existence and future of UFOs, stirring public interest and scientific discourse.

8. 1994 – Former U.S. President Richard Nixon died at the age of 81. Nixon was a central figure in American politics, especially known for his resignation following the Watergate scandal.

9. 2000 – In a landmark case, the governments of the United States and the United Kingdom agreed to release all their holdings of enriched uranium to combat nuclear proliferation.

10. 2013 – The Paris Agreement was opened for signature at the United Nations in New York City, aimed at addressing climate change by limiting global warming to well below 2 degrees Celsius.