However, the American historian Gerhard Weinberg noted: "...the enormous difficulties of air attacks on distant oil fields were not understood by either side at this time; it was assumed on both sides that even small air raids could bring about vast fire and destruction". Furthermore, the massive Italian defeats in the Balkans, the Horn of Africa and North Africa had pushed the Fascist regime in Italy to the brink of collapse by late 1940 with Mussolini becoming extremely unpopular with the Italian people. Hitler was convinced that if he did not rescue Mussolini, Fascist Italy would be knocked out of the war in 1941. Weinberg wrote the continuing Italian defeats "....could easily lead to the complete collapse of the whole system Mussolini had established, and this was recognized at the time; it is not hindsight from 1943". If Italy was knocked out of the war, then the British would be able to use the central Mediterranean again, and the governors of the French colonies in Africa loyal to the Vichy regime might switch their loyalties to the French National Committee headed by Charles de Gaulle. As Hitler had plans to ultimately use the French colonies in Africa as bases for the war against Britain, the potential loss of Vichy control over its African empire was seen as a problem by him. Furthermore, after Italy entered the war in June 1940, the danger of Axis air and naval attacks had largely closed the central Mediterranean to British shipping except for convoys to Malta, in effect closing the Suez canal as the British were forced to supply their forces in Egypt via the long Cape route around Africa. The British had made liberating Italian East Africa a priority to end the possibility of Italian naval and air attacks on British shipping in the Red Sea, which assumed greater importance because of the dangers posed to British shipping in the central Mediterranean. In turn, the decision by Field Marshal Archibald Wavell to deploy significant forces to the Horn of Africa while defending Egypt lessened the number of Commonwealth forces available to go to Greece. Although the performance of the Italian armed forces had been less than impressive, from the German perspective denying the British access to the central Mediterranean by stationing Luftwaffe and Kriegsmarine forces in Italy made it crucial to keep Italy in the war. Hitler ordered his Army General Staff to