Austrian army during the Napoleonic wars 1813-1818 - Cristini Luca Stefano

The Imperial and Royal or Imperial Austrian Army (German: Kaiserlich-königliche Armee, abbreviation 'K.K. Armee') was the armed force of the Holy Roman Empire under its last monarch, the Habsburg Emperor Francis II, although in reality, it was nearly all composed of the Habsburg army. When the Holy Roman Empire was dissolved in 1806, it assumed its title of the Army of the Austrian Empire under the same monarch, now known as Emperor Francis I of Austria.
The ancient name of 'Imperial-Royal Army' was used from 1745, as 'Royal' referred to the Apostolic Kingdom of Hungary, which was not part of the Holy Roman Empire, but under Habsburg rule.  The key feature of the army of the Austrian Empire during the Revolutionary and Napoleonic Wars (1792-1815) was that, due to the multi-national nature of the territories, regiments were split into German units (which included Czech-troops recruited from Bohemia, Moravia and Silesia, Polish and Ukrainian units recruited from the territory of Galicia, Flemings and Walloons territory of the former Austrian Netherlands, and Italians) and Hungarian units (which included troops from Croatia and Transylvania).