In August 1916 the Turkish Second Army started an offensive against the Russian front in eastern Turkey. On August 2, the Ottoman 16th Corps, together with strong Kurdish irregulars' support, attacked Bitlis and Mush. Fearing encirclement General Nazarbekov, the Russian commander, abandoned Bitlis on August 5. When Mush also fell, he decided to abandon Tatvan and the whole Mush valley and retreat to Ahlat. Around 18 August, the Russians having been reinforced, were able to counter-attack. By September the Turkish offensive was stalled and then turned. Nazarbekov advanced as the Turkish forces withdrew from Tatvan and Mush, but he did not have the available forces to hold Bitlis as winter approached. The Russian February Revolution in the spring of 1917 prevented any further Russian gains.