Before the war, Russia had the Russian Caucasus Army, but almost half of this was redeployed to the Prussian front after the defeats at the battles of Tannenberg and the Masurian Lakes, leaving behind just 60,000 troops in this theatre. In the summer of 1914, Armenian volunteer units were established under the Russian Armed forces. Nearly 20,000 Armenian volunteers expressed their readiness to take up arms against the Ottoman Empire as early as 1914. These volunteer units increased in size during the war, to the extent that Boghos Nubar, in a public letter to the Paris Peace Conference in 1919, stated that they numbered 150,000.