In 1945, Rendulic served as the commander-in-chief of Army Group Courland cut off in the Courland Pocket on the Eastern Front; Army Group North in Northern Germany; and Army Group Ostmark, in Austria and Czechoslovakia. On 7 May 1945, following the Soviet Prague Offensive, Lothar Rendulic surrendered Army Group Ostmark to the 71st Infantry Division of the U.S. Army in Austria. After his surrender, Lothar Rendulic was interned and tried in the Hostages Trial at Nuremberg, because of his involvement in the Wehrmacht's reprisals against civilians in Yugoslavia and the scorched earth policy in Lapland. On 19 February 1948 he was found guilty of war crimes and sentenced to twenty years in prison, although he was cleared of charges concerning the scorching of Lapland. Based upon the recommendations of the "Peck Panel", this sentence was later reduced to ten years, and on 1 February 1951 Rendulic was released from the military prison in Landsberg am Lech in Bavaria. After his release, he worked as an author and was involved in local politics in Seewalchen am Attersee, in the Salzkammergut region of Austria. He died at Fraham near Eferding, Austria, on 17 January 1971.