Today:
1500: Portuguese navigator Pedro Alvares Cabral and his fleet officially sighted the coast of Brazil.
1509: Henry VIII ascended the English throne following the death of his father, Henry VII.
1864: The United States Congress passed the Coinage Act of 1864, permitting the inscription In God We Trust on American coins.
1915: German forces released chlorine gas at the Second Battle of Ypres, marking the first large-scale use of chemical weapons in World War I.
1930: The United Kingdom, Japan, and the United States signed the London Naval Treaty to regulate submarine warfare and limit shipbuilding.
1944: Allied forces launched Operation Persecution, landing in the Hollandia area of New Guinea.
1970: The first Earth Day was celebrated in the United States, mobilizing millions of people to advocate for environmental protection.
1977: Optical fiber was used to carry live telephone traffic for the first time.
1993: The United States Holocaust Memorial Museum was dedicated in Washington, D.C.
2016: The Paris Agreement on climate change was opened for signature at the United Nations.