On 6 December 1934, his uncle Duke Charles Michael died, and George succeeded him as head of the House of Mecklenburg-Strelitz. He lived with his family at Schloss Remplin until April 1940, when the main part of the palace was burnt down. The Grand Ducal family then moved to Grunewald, where they lived until their home was destroyed in an Allied bombing raid in February 1944. In August 1944, George was arrested by the Gestapo and sent to Sachsenhausen concentration camp by the Nazi government, where he remained until February 1945. Following his release, Duke George and his family moved to Sigmaringen at the invitation of Princess Margarete of Hohenzollern (wife of Frederick, Prince of Hohenzollern) in March 1945.