As conflict escalated on the Eastern Front, so too did the use of dogs, and by the summer of 1941, 30 of the canine tank busters had arrived at the front line. How effective were these mostly Alsatian suicide bombers in battle? Not very. The dogs sooner sought out the familiar diesel-engine smell of the Soviet tanks than the petrol scent of their German counterparts; besides which they refused to dive under tanks that were now moving and were frightened off by the unknown noise of gunfire.