During Operation Barbarossa, the 30 June 1941 attack on Russia by Germany, the Panzerwaffe was virtually invincible until the appearance on the battlefront of the Russian Army's T-34 medium tank. In response to this new threat the Heereswaffenamt expedited the development of a new heavily armoured and powerfully armed medium tank. Given the designation Sonderkraftfahrzeug 171 (SdKfz 171) Panzerkampfwagen V (PzKpfwV) and named Panther, it entered the battle, during Operation Zitadelle (Citadel), at Kursk, July 1943. The first AusfDs proved to be very unreliable, but the much improved AusfA entered service followed by the Ausf G and soon the Panther was to become one of the most feared tanks on any battlefield of World War 2. Book jacket.