In 1939, at the start of the
Second World War, Thorne became GOC
48th (South Midland) Infantry Division, which played an important role in the
Battle of Dunkirk in 1940. He then became GOC
XII Corps, where he founded the innovative XII Corps Observation Unit as a prototype of the
Auxiliary Units guerrilla organisation. He became GOC
Scottish Command and
Governor of Edinburgh Castle in 1941 and was appointed a
Knight Commander of the Order of the Bath (KCB) in the
1942 Birthday Honours. Whilst in Scotland, he was involved in the creation of
War Office Selection Boards and responsible for the
Fortitude North deception plan, as well as preparation for the
Operation Doomsday the liberation of Norway. After the end of the war in Europe, German prisoners in Norway were reportedly forced to clear
minefields under British supervision. The Germans complained to Thorne but he dismissed the accusations arguing that the Germans prisoners were not prisoners of war but "disarmed forces who had surrendered unconditionally". By 1946, when the cleanup ended, 392 were injured and 275 had died; this was contrary to the terms of the
Geneva Conventions. He formally held the sovereignty of Norway until 7 June, when
Haakon VII of Norway returned from his exile. Thorne remained in charge of dismantling the German presence in Norway until he left the country on 31 October 1945. Thorne retired in 1946. ==Post-war years==