[2] In the Turkish War he was employed on the headquarters staff, becoming in 1788 major and personal aide-de-camp to the emperor, Joseph II and in 1789 was promoted to lieutenant colonel.

While Mack had been credited with the initial successes of March–April 1793, the ultimate failure of the coalition allies was also ascribed to him even though it was due to political and military factors over which he had no control.

He did all that was possible within the available time to reform the army, and on the opening of the war of 1805 he became quartermaster-general to the titular commander-in-chief in Germany, the Archduke Ferdinand Karl Joseph of Austria-Este, who was himself inexperienced in military command.

Consequently, Mack held the real responsible commander of the army that opposed Napoleon in Bavaria, but his position was ill-defined and his authority treated with minimal respect by the other general officers.

His own insecurities and vagaries did not encourage the confidence of the staff; in the campaigning that led up to the Battle of Ulm, Mack's frequent reversals of Viennese policy, and even his own decisions, further undermined an already fragile command structure.

A few of his officers, including Prince von Schwarzenberg, broke through the French defenses in a massed cavalry charge and escaped, but most of the Austrian high command was captured with 25,000 men, 18 generals, 65 guns, and 40 standards.

The general officers received a parole that required them to abstain from combat with France, removing the bulk of Habsburg commanders from the possibility of service in the upcoming campaign of the Upper Danube.

Upon his release in 1808, he lived in relative obscurity until 1819, when the ultimate victory of the allies had obliterated the memory of earlier disasters, he was, at the request of Prince Schwarzenberg, reinstated in the army as Feldmarschall-leutnant, and a member of the Order of Maria Theresa.