A combination of bad weather, the arguments of his generals, and a breach of security when the details of the original plan fell into Allied hands, eventually led Hitler to agree to postpone the attack until early 1940, when it was again delayed by the invasion of Denmark and Norway. In February, Hitler finally accepted the Manstein Plan. General Günther von Kluge's 4th Army and General Maximilian Reichsfreiherr von Weichs's 2nd Army were transferred from Army Group B to Rundstedt's command. General Ewald von Kleist was now to command Panzer (Armoured) Group Kleist, consisting of three armoured corps, led by Heinz Guderian, Georg-Hans Reinhardt and Hermann Hoth. These armoured corps were to be the spearhead of the German thrust into France. Although Manstein is often credited for the change of plans, he himself acknowledged Rundstedt's decisive role. "I would stress that my commander, Colonel-General von Rundstedt, agreed with my view throughout, and backed our recommendations to the full. Without his sanction we could never have kept up our attempts to change OKW's mind."