He raised an army of 12,000 men at the beginning of the Thirty Years' War in 1618. When Catholic League forces under General Tilly approached Baden in 1622 (Palatinate campaign), he marched against them, but came too late for the Battle of Mingolsheim. Setting off to pursue the retreating Catholics, he was defeated at the Battle of Wimpfen, and his army was destroyed, a few days later.