 He achieved his first major military successes in July 1634 during the "Actions for Regensburg" by regaining the city of Regensburg, which had been captured and occupied by the Swedes since November 1633.In August 1634 the city of Donauwörth was recaptured, which had been occupied by Sweden since April 1632.In September 1634 these successes were surpassed by the decisive victory in the Battle of Nördlingen (1634), a joint effort with the help of the Spanish forces under Cardinal Infant Ferdinand.