In January 1945, Mummert took command of the newly formed Panzer Division "Müncheberg" and was promoted to "generalmajor" (equivalent to the rank of brigadier general in the United States Army) on 1 February. His new unit, which was beginning to assemble in the area west of Berlin, was a division in name only and had relatively few armoured vehicles. It was activated in March 1945 and dispatched to the Eastern Front and defended Soviet attempts to cross the Oder River. It later fought in the Battle of Seelow Heights and had to gradually withdraw into Berlin and was engaged in fighting around the Zoobunker and the Tiergarten. Following the destruction of the last of his division's tanks near the Brandenburg Gate, Mummert was wounded on 1 May. Despite this he remained in command until his surrender to the Soviets on 4 May. After the war, he was held in a prisoner of war camp in Russia where he died in 1950.