[2] In 1742–1743, during the War of Austrian Succession, his father's regiment participated in the Battle of Sahay (Zahájí in Bohemia), and then in the siege of Prague, followed by duty in Bavaria and the Rhineland in 1743.

[4] The lack of accurate maps had hampered the conduct of the Seven Years' War and, in 1764, Schmitt was assigned to a project to improve the map-making capacity of the military.

In 1778, he was promoted to captain and mobilized against Prussia during the short War of the Bavarian Succession, after which he transferred back to the Balkan border areas where he stayed until 1782.

His work developing intelligence of Turkish strength in Osijek and Alt Gradiska satisfied his superiors and when the war actually broke out in 1787, he was assigned to the General Staff of the Slavonion Corps.

In March 1790, he transferred to Bohemia, under command of Field Marshal Ernst Gideon von Laudon, for anticipated action against the Kingdom of Prussia.

[7] Promotions [4] At the outbreak of the War of the First Coalition between the Habsburg monarchy and revolutionary France in April 1792, Schmitt was a staff officer in the main Imperial army in the Austrian Netherlands.

In the autumn of 1794, Schmitt organized the retreat of the main Imperial Army, now under the command of Coburg's successor, Feldzeugmeister Count Clerfayt, from their untenable positions in the Austrian Netherlands eastward to the Rhine.

[7] Schmitt's tenure as chief of staff was briefly interrupted in 1799 when he was connected, by rumour at least, to the 29 April assassination of the French delegates to the Congress of Rastatt.

On 1 March 1800, Schmitt was promoted to Feldmarschallleutnant, but later in that year, Emperor Francis II replaced his brother, Archduke Charles, as commander in chief of the army.

[7] During the War of the Third Coalition in 1805–1806, as one Austria's most capable chiefs of staff, Schmitt was called out of retirement for this specific task of organising the challenging Austro-Russian retreat.

On 11 November 1805, Kutuzov's column trapped one of Mortier's divisions, under command of Honoré Théodore Maxime Gazan de la Peyrière.

[12] When Napoleon's armies threatened Vienna in 1805, the Emperor called Schmitt out of retirement for the specific task of organizing the challenging Austro-Russian retreat.

After Schmitt's death, Weyrother, the architect of the Austrian defeat at Hohenlinden, developed the general battle plan of the Allied action at Austerlitz.

The military historian Digby Smith hypothesizes that Schmitt, an experienced officer and sound tactician, would have been more effective at the Battle of Austerlitz, at least more so than his replacement, Franz von Weyrother, as Chief of the Quartermaster General Staff of the Allied Army.

[13] Schmitt is mentioned in Leo Tolstoy's novel War and Peace, Volume I, where several Austrian court officials and generals express grief at the news of his death at Dürenstein.