Early in 1915 Hindenburg and Ludendorff surprised the Russian army that still held a toehold in East Prussia by attacking in a snowstorm and surrounding it in the Second Battle of the Masurian Lakes. "OHL" then transferred Ludendorff, but Hindenburg's personal plea to the Kaiser reunited them. Erich von Falkenhayn, supreme commander at "OHL", came east to attack the flank of the Russian army that was pushing through the Carpathian passes towards Hungary. Employing overwhelming artillery, the Germans and Austro-Hungarians broke through the line between and and kept pushing until the Russians were driven out of most of Galicia, in Austro-Hungarian Poland. During this advance Falkenhayn rejected schemes to try to cut off the Russians in Poland, preferring direct frontal attacks. Outgunned, during the summer of 1915 the Russian commander Grand Duke Nicholas shortened his lines by withdrawing from most of Poland, destroying railroads, bridges, and many buildings while driving 743,000 Poles,