Starting in the 1950s, he wrote for the popular magazine "Kristall". He first used the pseudonym Paul Karell, and later Paul Carell. He worked as a freelance author under various noms de plume for newspapers such as "Die Welt" and "Die Zeit" (as P. C. Holm, among others). He also wrote for the magazines "Norddeutsche Rundschau" and "Der Spiegel", and published some accounts of war stories for "Der Landser", a West German pulp magazine featuring stories predominantly set during World War II. He was seen as an influential adviser to the German Axel Springer AG, where he wrote speeches for Axel Springer. From 1965 to 1971 the Office of the State Prosecutor of Verden in Germany investigated him for murder. But the investigation, which some claim should have clarified his role in the genocide of Hungarian Jews, ended without an indictment. Schmidt never had to face a trial for his activities during the war. In 1992 Carell claimed that even after the Battle of Stalingrad there was a possibility for Germany to win the war. In his view, it was primarily the command of Adolf Hitler that led to the defeat. The leadership of the Wehrmacht and very competent commanders such as Erich von Manstein could have achieved victory if not for Hitler's interference. Carell also claimed that the invasion of the Soviet Union was a preemptive attack to forestall an invasion of Germany by the Red Army. The success of his books "Hitler Moves East (Unternehmen Barbarossa)" and "Scorched Earth (Verbrannte Erde)" made Carell a leading post-war chronicler of the German side of World War II on the Eastern Front. His book "Die Gefangenen" (1980), dealing with German prisoners of war in the Soviet Union, was published by Ullstein-Verlag. These books generally had a positive media reception; "Die Welt" wrote, for example: "Helps to reduce the dislike between Germans and Russians (...) qualified as an historian." Or the "": "Someone for whom the seriousness of the source and the value of documentation are more important than going for cheap thrills – that is Paul Carell!" Carell also wrote about Rommel and about the Allied invasion of Normandy. In his books, Carell portrays the Wehrmacht as heroes fighting for a lost cause. Carell presents the post-war revisionist messages first popularized by leading Wehrmacht ex-generals:  Critics point out that Carell's works emphasize the German army's professionalism, sacrifice and positive encounters with civilians, and his books also suggest that the Wehrmacht freed the Russians from their Communist tyrants and restored their religious community.