Sweden wins a major victory at the Battle of Breitenfeld against the Holy Roman Empire during the Thirty Years' War.
The Battle of Breitenfeld (German: Schlacht bei Breitenfeld; Swedish: Slaget vid Breitenfeld) or First Battle of Breitenfeld (in older texts sometimes known as Battle of Leipzig), was fought at a crossroads near Breitenfeld approximately 8 km north-west of the walled city of Leipzig on 17 September (Gregorian calendar), or 7 September (Julian calendar, in wide use at the time), 1631. It was the Protestants' first major victory of the Thirty Years War.
The victory confirmed Sweden's Gustavus Adolphus of the House of Vasa as a great tactical leader and induced many Protestant German states to ally with Sweden against the German Catholic League, led by Maximilian I, Elector of Bavaria, and the Holy Roman Emperor Ferdinand II.