When the American armies penetrated Bavaria and western Austria at the end of April, they met little organized resistance, and the National Redoubt was shown to have been a myth. The alleged Alpine Fortress was one of three reasons associated with SHAEF's movement of forces towards southern Germany rather than towards Berlin, the other two being the fact that the city was planned to be in the Soviet Zone of Occupation, and that the battle for it would have entailed unacceptably high Western Allied casualties.