Hitler realized the mistake too late

On 9 July the Allies invaded Sicily in Operation Husky. German signals intercepted by GC&CS showed that even four hours after the invasion of Sicily began, twenty-one aircraft left Sicily to reinforce Sardinia. For a considerable time after the initial invasion, Hitler was still convinced that an attack on the Balkans was imminent, and in late July he sent General Erwin Rommel to Salonika to prepare the defence of the region. By the time the German high command realised the mistake, it was too late to make a difference.