The imperial commander defeated at the First Battle of Breitenfeld in 1631 was Johann Tserclaes, Count of Tilly.
The battle took place on 17 September 1631 near Leipzig during the Thirty Years’ War. A combined Swedish-Saxon army led by Gustavus Adolphus and John George I defeated Tilly’s Imperial-Catholic League force. The victory was a major breakthrough for Sweden and the Protestant cause.
Tilly had been one of the most successful Catholic commanders of the war, but Swedish artillery, flexible formations, and coordinated cavalry attacks broke his army. He was wounded several times during the fighting and escaped with help from his officers. Pappenheim also commanded forces at Breitenfeld, which explains why he is a tempting alternative, but Tilly was the army’s senior commander and the defeated imperial leader.
The defeat shattered Tilly’s previously formidable reputation and opened southern Germany to Gustavus Adolphus. It was also the first major defeat suffered by the Catholic forces in the war.