1.With the start of the Russian Revolution a strange situation was created in North Eastern Turkey: (a) the Armenians in the area founded the new Armenian Republic out of the old Russian Province of Yerevan; (b) the Russian troops disappeared, and what was left were tzarist Russian officers, Russian Transcaucasian troops (mostly Armenians) and Armenian guerrilla bands.
2.The result was that even before the Ottoman army returned to the region, the Armenian forces in Eastern Turkey had begun to retreat in a northerly direction toward what was to become their new homeland. During the retreat they committed "unspeakable" horrors against the Turks, the Kurds and Circasians. "Unspeqakable" is used literally--for it is difficult to believe that anyone wants to tell in great detail about the gouging of eyes, the people buried alive, the burning of mosques full of women, children and old men.
3.On their side the Turks of Transcaucasia fled into Anatolia. Thus everybody was again relocated in one way or other. The warfare between Armenians and Turks resumed in 1919-1920 when the Turkish army (no longer the Ottoman, but the Nationalist) re-conquered Eastern Turkish cities and territories still occupied by the armenians, and the present frontiers between Armenia, Russia, and Turkey were eventually established by negotiation.
4.However, many Armenians who had been relocated to Syria and Lebanon now formed the Armenian Legion and joined the French forces which had occupied that Ottoman Province after the armistice of 1918. Together with the French they invaded South Eastern Turkey, and the region called Cilicia. Again, a great many horrible things happened, but the campaign was relatively short, because General Mustafa Kemal (Ataturk) had by then taken charge in Eastern Turkey, and the French realizing that annexing Cilicia was not going to be easy decided to stop fighting and start negotiating. The Armenian Legion withdrew to Syria destroying everything and killing almost everybody on its way.