commander who was in radio communication with his superiors. Thus the basic design of the main battle tanks called for a larger turret that would house the tank commander, gunner and loader, while a driver and a machine gunner were down in the hull. Guderian insisted on the tank commander being in radio communication with both his platoon and with the members of his own tank crew. Though the Panzer III was conceived as the main battle tank of the Wehrmacht, the Wehrmacht did not anticipate being at war with Europe's major powers in 1939, and few were available at the start of the war. Excluding Czech-built tanks, on 1 September 1939 the invasion of Poland was undertaken with the German armoured force of 3,195 tanks evenly split between the Pz I training tank and the Pz II light tank; of the main battle tanks, only 98 Pz IIIs were in service during the invasion of Poland, along with 211 Pz IVs, with 215 tanks of various models also available as command tanks after being modified by having their main armament removed and extra communications equipment installed. Manufacturing Control The production of tanks in Germany began in 1934. Due to the insertion of the Nazi Party into the procurement process and political considerations that had nothing to do with the goal of providing arms for the military, the companies that ended up gaining the contracts for tank production had limited actual experience in mass production. Ford and Opel, two manufacturers with considerable knowledge and ability in assembly line techniques, were not allowed to participate in the bidding process. Germany in general and the German tank production industry in particular was not prepared for the total war that Germany was entering in 1939. In contrast to the Messerschmitt 109 fighter aircraft, which was designed by Willy Messerschmitt with the production of large numbers of the aircraft in mind, tank design and production in Germany in 1939 was the work of craftsmen. German industry anticipated supporting the military in brief conflicts. A full commitment to war production was not made until the midpoint in the conflict. Surprisingly, civilian vehicle production was not set aside until 1943. By contrast British car companies switched to war production (making military transports, aircraft and tanks) at the start of the war and the United States halted production of civilian automobiles within two months of its entry