February 12 1918, Erzincan–The Russians had had great success in the Caucasus in 1916, pushing as far west as Erzincan. The February Revolution, bringing with it demands for a peace without annexations, precluded any further offensive deeper into Turkish territory in 1917. The Brest-Litovsk armistice officially halted fighting in December, but the Young Turks saw Russian weakness as an opportunity to fulfill their ambitions in the Caucasus that had been deferred after the defeat at Sarikamish in early 1915.
The Bolsheviks’ abrupt departure from the Brest-Litovsk talks, along with Russian demobilization, provided the perfect opportunity for the Turks to begin a new offensive in the Caucasus. While this technically violated the armistice, the Russians had also violated it by demobilizing, and the Turks were, in their own view, simply reclaiming their own territory that was now illegally occupied by the Russians. They had also been spreading false propaganda about massacres of the Turkish population behind Russian lines to justify the attack.
The vast majority of the defenders had left back for Russia long before the demobilization order was given. The only remaining forces were Armenian and Georgian troops, numbering perhaps 20,000 over the whole front. The first shots were fired on February 12 outside Erzincan; the Armenians, outnumbered possibly twenty-to-one, began a winter retreat through the mountains to Erzurum. They were followed by a trail of Armenian refugees who had escaped the genocide in 1915, returned the the area with the Russians, and were now forced to flee once again.
Sources include: Roger Ford, Eden to Armageddon; Raymond Kévorkian, The Armenian Genocide.