Ottoman Sipahi cavalryman, circa 1550

Armour and weapons of an Ottoman Sipahi cavalryman, circa 1550, on display at the Musée de l'Armée in Paris, France.

The feudal-based sipahi cavalry were a core feature of Ottoman armies from the Fifteenth through to the late Eighteenth centuries. The sipahi's were professional mounted warriors granted a land fief in trust from the Sultan. The income from this fief allowed the sipahi to maintain his horse, weapons and equipment, and in return he had to be available for military service whenever the Sultan required it. On mobilisation sipahis from the same region were formed into units of up to 1000 horsemen each. By the Sixteenth century it is estimated that the Ottoman army could put 40,000 sipahis into the field. Originally raised from Turks in Anatolia the sipahi system was also extended into the new territories and populations of Ottoman controlled Europe - 'Rumelia' - as the Empire grew.

At the peak of their strength the sipahis were the spearhead of the powerful Ottoman armies that invaded the Balkans, conquered all of southeast Europe and struck fear across the rest of the West. The superior discipline, organisation and size of these armies compared to their European opponents made them all but invincible for the better part of three centuries of warfare. Only with the defeat of the last Ottoman attempt to capture Vienna in 1683 was the Ottoman threat to Europe finally broken.