This is a pioneering historical investigation of the Assyrian, Chaldean, and Syrian Christian minorities during World War I, who suffered the same fate as the Armenians. Ethnic cleansing and large-scale massacres occurred throughout northern Mesopotamia and parts of Ottoman-occupied Iran. Based on primary sources from official archives, as well as hitherto unused manuscript sources and oral histories published here for the first time, this book attempts to give a full picture of the events of 1915. The book concentrates on the Assyrians of Urmia and Hakkari and on the Syrians of Diyarbekir province, particularly in Tur Abdin.