ヴァグラムの戦い
But before this came about, in 1809 tensions between Austria and France became intense. William did not hesitate to join the Austrian army as a "Feldmarschalleutnant" (major-general) in May 1809 As a member of the staff of the Austrian supreme commander, Archduke Charles he took part in the Battle of Wagram, where he was wounded in the leg.