Wikipedia:Selected anniversaries/July 1
- 1520 - La Noche Triste: Spanish Conquistadors under Hernán Cortés (pictured) barely succeeded in escaping from the Aztec capital of Tenochtitlan.
- 1569 - The Union of Lublin was signed, merging the Kingdom of Poland and the Grand Duchy of Lithuania into a single state, the Polish-Lithuanian Commonwealth.
- 1867 - The British North America Act came into effect, uniting the Province of Canada, New Brunswick, and Nova Scotia into the Canadian Confederation.
- 1916 - World War I: The first day of the Battle of the Somme became the bloodiest day in the history of the British Army, with 57,470 casualties of which 19,240 were killed or died of wounds.
- 1991 - The Warsaw Pact was officially dissolved at a meeting in Prague.