He was not employed for some years, but in 1804, when the war party in the Austrian court needed a general to oppose the peace policy of the Archduke Charles, Mack was made quartermaster-general of the army, with instructions to prepare for a war with France. 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. Furthermore, the restructuring of the Habsburg military had been incomplete; Mack chose to initiate some of Charles' innovations, while ignoring others. 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.