The Imperial Army (German: Kaiserliche Armee), Imperial Troops (Kaiserliche Truppen), or Imperialists (Kaiserliche) for short, was a name used for several centuries, especially to describe soldiers recruited for the Holy Roman Emperor during the Early Modern Period. The Imperial Army of the Emperor should not be confused with the Army of the Holy Roman Empire (Reichsarmee), which could only be deployed with the consent of the Imperial Diet. The Imperialists effectively became a standing army of troops under the Habsburg emperor from the House of Austria, which is why they were also increasingly described in the 18th century as "Austrians", although its troops were recruited not just from the Archduchy of Austria but from all over the Holy Roman Empire of the German Nation.
The Habsburg monarchy supplied almost all the Holy Roman Emperors during the Early Modern Period. Their title of Emperor was one that was bound not so much to a territory, but to a person. In the tradition of the Roman Empire, the Emperor had a status that was recognised in all of Latin Europe.
Accordingly, the Imperial Army was a force established by the Emperor, with privileges in the whole of the Holy Roman Empire. The Emperor was not permitted to raise troops in the electoral states, but had inter alia the right to recruit soldiers in the imperial cities and in all other territories.
During the imperial interregnum of 1740-1742, Habsburg troops no longer formed the army for the Emperor, but that of the Queen of Hungary. During the Austrian War of Succession, Queen Maria Theresa and the Austrian House of Habsburg, fought for their survival within the European system of power. She initially lost her battle for the imperial crown for her husband, Francis Stephen of Lorraine. With the acquisition of the crown by Charles VII of the Bavarian House of Wittelsbach, units from the Electorate of Bavaria formed the Imperial Army for a short time, from 1742 to 1745. A year after the loss of the imperial crown, the Archduchess of Austria and Queen of Hungary directed her troops to wear green instead of gold for officers' sashes and for the regimental flags. Gold has always been considered an imperial attribute.
After the imperial election of Maria Theresa's husband, Francis I, the Habsburg troops were given back their imperial status. Although Maria Theresa took the title of empress, she put no value on her coronation as empress. This was reflected in the title of her army, which was now called "Roman Imperial-Royal" (römisch kaiserlich-königlich). The colloquial, shorter term, "Austrian", established itself during the Seven Years' War (1756-1763) and subsequent conflicts in the War of Bavarian Succession (1778/1779), the Russo-Austrian war against the Turks (1787-1792) and the Napoleonic Wars.
Prussian and Protestant journalists increasingly lost interest in a universal Reich concept, which, for a long time, had earned the imperial troops their special position. Even Maria Theresa's son, Emperor Joseph II, with his centralizing reforms that promoted an Austrian territorial state, encouraged imperial politics less and less. In 1804, the Austrian imperial crown was introduced. Only two years later, the Austrian emperor laid down his Roman-German Emperor's crown. Until 1871, there was only an Austrian imperial crown in the German nation.
During the Early Modern Period, the Imperial Army fought in all the wars affecting the Empire, usually allied with the Army of the Holy Roman Empire and other territorial forces.
The Thirty Years' War led to an unusually strong arming of the Emperor. In 1635, the Imperial Army reached a peak of 65 regiments of foot, with a nominal strength of 3,000 men each. During the course of the war, 532 regiments were formed and disbanded. In 1648 only 9 regiments of foot, 9 regiments of horse and a regiment of dragoons remained.
Gradually, a standing imperial army evolved as a result of the many wars. Of the 49 regiments raised for the Second Northern War, 23 remained in 1660. The 1760s saw 28 new regiments being formed, and the following decade saw a further 27.