On 30 January 1945 Ahlfen was promoted to major general and appointed by Field Marshal Ferdinand Schörner as the commandant of the city of Breslau which Adolf Hitler had declared in August 1944 to be a ‘fortress’, to be defended at all costs. He was soon in conflict with the "Gauleiter" of the city Karl Hanke who had been declared Breslau’s “battle commander” by Hitler. Hanke advocated a breakout using parachute troops which Ahlfen did not consider realistic and he disagreed with him on several other issues, including the construction of an auxiliary airstrip that would be less vulnerable to attack. On the orders of Schörner and at the instigation of Hanke he was replaced as commandant by General of the Infantry Hermann Niehoff on 5 March 1945. Great loss of life and destruction then followed during the Siege of Breslau as Soviet forces sought to capture the city which held out for two months defended partly by elderly "Volkssturm" home guard and boys from the Hitler Youth, with little defence against air attacks.