<P> In 1915 the German command decided to make its main effort on the Eastern Front, and accordingly transferred considerable forces there . To eliminate the Russian threat the Central Powers began the campaign season of 1915 with the successful Gorlice - Tarnow Offensive in Galicia in May 1915 . </P> <P> After the Second Battle of the Masurian Lakes, the German and Austro - Hungarian troops in the Eastern Front functioned under a unified command . The offensive soon turned into a general advance and a corresponding strategic retreat by the Russian Army . The cause of the reverses suffered by the Russian Army was not so much errors in the tactical sphere, as the deficiency in technical equipment, particularly in artillery and ammunition as well as the corruption and incompetence of the Russian officers . Only by 1916 did the buildup of Russian war industries increase production of war material and improve the supply situation . </P> <P> By mid-1915, the Russians had been expelled from Russian Poland and hence pushed hundreds of kilometers away from the borders of the Central Powers, removing the threat of Russian invasion of Germany or Austria - Hungary . At the end of 1915 German - Austrian advance was stopped on the line Riga--Jakobstadt--Dünaburg--Baranovichi--Pinsk--Dubno--Ternopil . The general outline of this front line did not change until the Russian collapse in 1917 . </P> <P> After the Battle of Sarikamish, the Russo - Turkish front quickly turned in favor of Russian forces . The Turks were concerned with reorganizing their army and committing the Armenian Genocide . Meanwhile, Russia was preoccupied with other armies on the Eastern Front . However, the appointment of Grand Duke Nicholas Nikolaevich as Viceroy and Commander in the Caucasus in September 1915 revived the situation of the Russo - Turkish front . </P>

What country surrendered to germany essentially ending the war on the eastern front