Distinguishing himself in the Austro-Turkish War (1787–1792) for his vigor in defending his sector of Croatia, von Hiller was made lieutenant colonel in 1788 and was awarded the Knight’s Cross of the Order of Maria Theresa.

In 1796 von Hiller commanded a brigade in the Army of the Rhine, but ill health compelled him to retire.

When war with France broke out in 1809, von Hiller was given command of VI Armee Korps covering the left wing of the main Austrian army.

When Emperor Napoleon I of France fell on the Austrian left wing on 20 April at the Battle of Abensberg, Hiller arrived and took command of the V, VI, and II Reserve Armeekorps.

Not realizing he was alone on the south bank, Hiller attacked Marshal of France Jean-Baptiste Bessières and won a minor victory in the Battle of Neumarkt-Sankt Veit on 24 April.

His corps fought well during the desperate two days of fighting in the town of Aspern and contributed materially to the Austrian victory.