 Bradley and Buell conclude that " although no single segment of the Balkan campaign forced the Germans to delay Barbarossa , obviously the entire campaign did prompt them to wait . " On the other hand , Richter calls Eden 's arguments a " falsification of history " . Basil Liddell Hart and de Guingand point out that the delay of the Axis invasion of the Soviet Union was not among Britain 's strategic goals and as a result the possibility of such a delay could not have affected its decisions about Operation Marita . In 1952 , the Historical Branch of the UK Cabinet Office concluded that the Balkan Campaign had no influence on the launching of Operation Barbarossa . According to Robert <unk> , " the main causes for deferring Barbarossa 's start from 15 May to 22 June were incomplete logistical arrangements and an unusually wet winter that kept rivers at full flood until late spring . " This however does not answer whether in the absence of these problems the campaign could have begun according to the original plan . Keegan writes : 
