their controllers and this made the trainers unwilling to work with new dogs. Some went so far as to say that the army did not stop with sacrificing people to the war and went on to slaughter dogs too; those who openly criticized the program were persecuted by "special departments" (military counterintelligence). Out of the first group of 30 dogs, only four managed to detonate their bombs near the German tanks, inflicting an unknown amount of damage. Six exploded upon returning to the Soviet trenches, killing and injuring soldiers. Three dogs were shot by German troops and taken away without attempts by the Soviets to prevent this, which provided examples of the detonation mechanism to the Germans. A captured German officer later reported that they learned of the anti-tank dog design from the dead animals, and considered the program desperate and inefficient. A German propaganda campaign sought to discredit the Red Army, saying that Soviet soldiers refuse to fight and send dogs instead. Another serious training mistake was revealed later; the Soviets used their own diesel engine tanks to train the dogs rather than German tanks which had gasoline engines. As the dogs relied on their acute sense of smell, the dogs sought out familiar Soviet tanks instead of strange-smelling German tanks. The efficacy of using anti-tank dogs in World War II remains uncertain. There are claims by the Soviet sources that around 300 German tanks were damaged by Soviet anti-tank dogs. This claim was considered propaganda by many Russian historians who believed it was meant to justify the dog training program. There are, however, documented claims of individual successes of the program, with the number of damaged tanks usually being within a dozen. For example, at the front of the 160th Infantry Division near Hlukhiv, six dogs had damaged five German tanks; near the airport of Stalingrad, anti-tank dogs destroyed 13 tanks. At the Battle of Kursk, 16 dogs disabled 12 German tanks which had broken through the Soviet lines of defence near Tamarovka, Bykovo. The German forces knew about the Soviet dogs from 1941 onwards, and so took measures to defend against them. An armored vehicle's top-mounted machine gun proved ineffective due to the relatively small size of the attackers as the dogs were too low to the ground and because of the dogs' speed and the difficulty in spotting them. Consequently, every German soldier received orders to