According to historian Antony Beevor, in contrast, Soviet aviation apparently succeeded in destroying more than 500 Luftwaffe aircraft on the ground. The Soviet deception efforts were so successful that German estimates issued in mid-June placed the total Soviet armoured strength at 1,500 tanks. The result was not only a vast underestimation of Soviet strength, but a misperception of Soviet strategic intentions. The main tank of the Soviet tank arm was the T-34 medium tank, on which the Red Army attempted to concentrate production. The tank arm also contained large numbers of the T-70 light tank. For example, the 5th Guards Tank Army roughly contained 270 T-70s and 500 T-34s. In the salient itself the Soviets assembled a large number of lend-lease tanks. These included U.S.-manufactured M3 Lees and British-built Churchills, Matildas and Valentines. However, the T-34 made up the bulk of the Soviet armour. Without including the deeper reserves organised under the Steppe Front, the Soviets massed about 1,300,000 men, 3,600 tanks, 20,000 artillery pieces and 2,792 aircraft to defend the salient. This amounted to 26 percent of the total manpower of the Red Army, 26 percent of its mortars and artillery, 35 percent of its aircraft and 46 percent of its tanks. Contest for aerial supremacy By 1943 the Luftwaffe's strength on the Eastern Front had started to weaken after Stalingrad, and the siphoning of resources to North Africa. The Luftwaffe forces in the east were further depleted with fighter units being shifted back to Germany to defend against the escalating Allied bombing campaign. By the end of June, only 38.7 percent of the Luftwaffe's total aircraft remained in the east. In 1943 the Luftwaffe could still achieve local aerial superiority by concentrating its forces. The majority of German aircraft left available on the Eastern Front were slated for Citadel. The goal of the Luftwaffe remained unchanged. The priority of the German air fleet(s) was to gain aerial supremacy, then to isolate the battlefield from enemy reinforcements, and finally, once the critical point had been reached in the land battle, to render close air support. The changing strengths between the two opponents prompted the Luftwaffe to make operational changes for the battle. Previous offensive campaigns had been initiated with Luftwaffe raids against opposing airfields to achieve aerial superiority. By this point in the war Red Army equipment reserves were extensive and the Luftwaffe commanders realised that aircraft could be