What was the situation on eastern front in the early part of 1915

Bristish forces invaded Turkey at Gallipoli and helped the Russians repel German and Austrian advances is actually wrong. That was the goal of the Gallipli operation, but it failed. The Russians were unable to repel the Germans. The Turks joined German and Austrian forces to drive the Russians back into Russian territory is better, but the initial Turkish campaigns against Russia were pretty dismal failures, and the Austrians likewise had very little success until the Germans took direct control of the Austrian army. But the German army did push the Russians back pretty significantly.