 Complete the following phrase:  On the battlefields far from Bulgaria, the war had entered a long period of stalemate with no side appearing to gain the upper hand. On the Western Front in February 1915, the French failed to break the German lines at the First Battle of Champagne, while further attempts at the Second Battle of Artois during May also came to an unsuccessful conclusion. The Germans had decided to focus their efforts on the Eastern Front, where they had considerable success against the Russians in the Second Battle of the Masurian Lakes in February 1915, but their gains were largely negated at the 