Mackensen remained with the army after the war and was promoted to lieutenant colonel in 1932. The next year, he became chief of staff of the cavalry corps. He was promoted to colonel in September 1934, Generalmajor (U.S. equiv. brigadier general) in January 1939, and Generalleutnant (U.S. equiv. major general) in January 1940. He briefly served as chief of staff of Fourteenth Army (from September to November 1939) and then as chief of staff of Generaloberst (U.S. equiv. full general) Siegmund Wilhelm List's Twelfth Army (from November 1939 to January 1941). He participated in the invasion of France and received promotion to General der Kavallerie (U.S. equiv. lieutenant general) in August 1940.
In January 1941, Mackensen took command of the III Corps (Motorized). His seizure of bridgeheads at Dnepropetrovsk during the invasion of the Soviet Union assisted Generaloberst Ewald von Kleist's breakthrough. Units of his corps captured and briefly held Rostov in late 1941. In January 1942, the III Corps was redesignated the III Panzer Corps. It remained engaged in the Ukraine and Caucasus areas. Mackensen's forces crossed the Terek River in late 1942 before having to withdraw in consequence of the Soviet offensive at Stalingrad.
Mackensen assumed command of the First Panzer Army in November 1942 and was promoted to Generaloberst in July 1943. His army took part in Field Marshal Erich von Manstein's counteroffensive and recapture of Kharkov in February and March 1943, and his forces pushed to the Donets River in the area east of Petrovskoye. Over the summer, the First Panzer Army was gradually forced out of the Donets Basin and back toward the Dnieper River at Zaporozhye and Dnepropetrovsk. Mackensen was compelled to give up the German bridgehead on the Dnieper at Zaporozhye by mid-October 1943.
That November, Mackensen assumed command of the reconstituted Fourteenth Army in Italy. His forces engaged the Allied landing at Anzio on 22 January 1944 and contained the Allies there for several months. Mackensen did not get along well with Field Marshal Albert Kesselring, commander of German forces in Italy, who thought him at times too parochial in his operational conduct. Hitler blamed Mackensen for the loss of Rome and relieved him of command in June 1944. He did not again have a command in the war.
Following the war, Mackensen was tried for the Ardeatine Caves Massacre and was sentenced to death on 30 November 1945; the sentence was then commuted to life imprisonment. He was released from Werl Prison in October 1952. He contributed two articles to the postwar German Military History Series and, in 1967, published a book on the 1941–1942 Eastern Front Campaign of the III Panzer Corps. Mackensen died in Altmühlendorf near Nortorf, Schleswig-Holstein, Germany, on 19 May 1969.
Jon D. Berlin
Brett-Smith, Richard. Hitler's Generals. San Rafael, CA: Presidio, 1977.; Carell, Paul. Hitler Moves East. Trans. Ewald Osers. Boston: Little, Brown, 1965.; Mackensen, Eberhard von. Vom Bug zum Kaukasus: Das III. Panzerkorps im Feldzug gegen Sowjetrussland 1941/42. Neckargemünd, Germany: Vowinckel, 1967.; Ziemke, Earl F. Stalingrad to Berlin: The German Defeat in the East. Washington, DC: Center of Military History, 1984.