On 24 April 1915, Muslim Turkish authorities of the Ottoman Empire detained 250 Christian Armenian intellectuals and community leaders in the Ottoman capital Constantinople (modern Istanbul). Although there had been many massacres of Armenians in the past, 24 April saw the start of a systematic, well planned, and state sponsored scheme to remove Christians, mostly Armenian, and to a lesser extent Greek and Assyrian, from the Ottoman Empire.
The Armenian Genocide was done under the pretext that they formed a fifth column inside the country after the Ottoman Empire joined the side of German and Austria-Hungary in the First World War. 1.5 million Armenians were murdered or starved to death over the next five years, but most in 1915. The US Ambassador to the Ottoman Empire, Henry Morgenthau, extensively documented the genocide, and routinely called it “race extermination”
Thirty years later, Hitler used the world’s non-reaction to the Armenian Genocide to move ahead with his Final Solution of the Jews and other undesirables.