Arnim continued in the Reichswehr after the war, and in 1935 he took command of the 69th Infantry Regiment. Advanced to Generalmajor (U.S equiv. brigadier general) in January 1938, von Arnim took charge of an Army Service Depot at Schweidnitz in Silesia during 1938 and 1939.
Following the outbreak of World War II, on 12 September 1939 von Arnim took command of the 52nd Infantry Division. He was promoted to Generalleutnant (U.S. equiv. major general) in December 1939. In October 1940, he shifted to head the 17th Panzer Division and led it in Operation barbarossa, the German invasion of the Soviet Union.
Assigned to Major General Heinz Guderian's 2nd Panzer Group, von Arnim proved his mettle as a panzer commander. Seriously wounded near Schklov on 27 June 1941, von Arnim did not return to action until September and participated in the encirclement of Kiev later that month. His forces then took the important railway junction of Bryansk. Shortly after the victory at Bryansk, von Arnim was promoted to General der Panzertruppen (U.S. equiv. lieutenant general) effective in October 1941. He then commanded the XXXIX Motorized Corps, which became a panzer corps in July 1942, and saw action at Tikhvin and Cholm. Arnim was promoted to Generaloberst (U.S. equiv. full general) in December 1942 and assumed command of the Fifth Panzer Army in Tunisia.
Following meetings with Adolf Hitler, Arnim assumed command of Axis forces in Tunisia on 9 December 1942. His performance in this role has drawn criticism from historians. Arnim and Field Marshal Erwin Rommel often worked at cross-purposes, and Arnim failed to take advantage of Rommel's victories at Kasserine and Tebersa. Arnim's own attack by the Fifth Panzer Army in February 1943 toward Medjez el Bat and Beja failed, even though he won a series of tactical victories. Following those events, Arnim received command of Army Group Africa on 9 March 1943.
British forces took Arnim prisoner on 12 May 1943. Incarcerated in an English country house at Hampshire until his release in 1947, Arnim then took up residence in Bad Wildungen, Germany, where he died on 1 September 1962.
Breuer, William B. Operation Torch. New York: St. Martin's Press, 1985.; Mitcham, Samuel W., Jr. "Arnim: General of Panzer Troops Hans-Jürgen von Arnim." In Correlli Barnett, ed., Hitler's Generals, 335–358. London: Weidenfeld and Nicolson, 1989.