Browse Historical Events by Day: What Happened on December 31st?

The Julian calendar is introduced by Julius Caesar, with January 1, 45 BCE, as its first day.

Pope Sylvester II dies, marking the end of his papacy, during which he contributed to the advancement of science and mathematics in Europe.

The coronation of Stephen I as the first Christian king of Hungary, a significant event in the Christianization of the Hungarian people.

The British suffer heavy losses in the Battle of Princeton during the American Revolutionary War.

The estimated population of the world reaches 3.45 billion, according to the United Nations.

The Panama Canal is transferred from U.S. control to Panamanian ownership.

The United Kingdom officially completes its transition out of the European Union, fully implementing Brexit.