Thälmann was also leader of the paramilitary Roter Frontkämpferbund (which was banned as extremist by the governing social democrats in 1929). In 1932 he established Antifaschistische Aktion. He was arrested by the Gestapo in 1933 and held in solitary confinement for eleven years; for political reasons, Stalin did not seek his release when he entered into the Molotov–Ribbentrop Pact with Germany, and Thälmann's party rival Walter Ulbricht ignored requests to plead on his behalf. Many of Thälmann's closest associates who had emigrated to the Soviet Union were executed during the Great Purge of the 1930s. Thälmann was shot on Adolf Hitler's personal orders in Buchenwald in 1944.