By early 1943, the failure to overcome the Soviet Union, including the disastrous defeat at Stalingrad, defeats in North Africa, and increasing Allied bombing of Germany had substantially weakened many Germans' allegiance to the Nazi regime. The conspirators decided it was time for the "spark". General Friedrich Olbricht, who controlled the "Ersatzheer" (Replacement Army) set up a plan for Replacement Army troops to seize control of Germany after Hitler was killed. Tresckow was now serving as Chief Operations Officer of Army Group Centre (AGC) on the Eastern Front. AGC commander Günther von Kluge knew of Tresckow's activities, but did not denounce him to the Gestapo, nor participate himself. He allowed Tresckow to put several other anti-Nazi officers on the AGC staff, but he also tried to dissuade Tresckow from taking action.