After his victory at the Battle of Breitenfeld, the Swedish king Gustavus Adolphus conquered large parts of northern and central Germany in 1631.

[1] Part of the Swedish army under General Horn remained active and conquered several places in Franconia.

Tilly gathered the garrisons from the Upper Palatinate and added 8,000 men of the Bavarian militia to his army.

Gustavus Adolphus needed another victory after the Swedish defeat to convince his various German allies, such as Württemberg, to continue supporting Sweden.

A week later he captured Donauwörth, murdering surrendering Catholic troops and friendly Protestant burghers and gathered enough men to invade Bavaria.