During World War I the Ottoman Empire sided with Germany , the Austro-Hungarian Empire and Bulgaria against the British Empire , France and the Russian Empire . In northern Mesopotamia , northern Syria and south east Turkey the Ottomans held the armed support of the Kurds , Turcomans , Circassians and some Arab groups , while the British and Russians were militarily supported by the Assyrians and Armenians ( particularly in the wake of the Armenian genocide and Assyrian genocide ) , and some Arab groups . The Ottomans were defeated , and in 1918 the British occupied Mosul , and indeed the whole of Iraq
Assyrian genocide
Assyrian genocide
Mosul