However, after serving against the Turks and Tatars during the Russo-Turkish War for a short time as captain and major of cavalry, he was accused of bad conduct, brutality, and disobedience and condemned to death.

Trenck's Pandurs soon became infamous for the atrocities they committed on the civilian population, some actions deemed brutal even by the standards of the day.

[3] When the War of the Austrian Succession broke out Trenck rallied volunteers and marched for Vienna to assist Maria Theresa.

[citation needed] At the Battle of Soor, he and his irregulars plundered when they should have been fighting and Trenck was accused of having allowed King Frederick the Great himself to escape.

Much was allowed to an irregular officer in all these respects, but Trenck had far outrun the admitted limits, and above all his brutalities and robberies had made him detested throughout Austria and Silesia.

Nonetheless, concerns about the apparently arbitrary form of the proceedings meant that eventually the sentence was commuted by the Empress into one of cashiering and imprisonment.