outside world, and to perform intelligence work. In October, he parachuted into Norway and became a leader of the Milorg group. In that same month he also became head of the newly established Oslo Gang, a sabotage group, whose other members were Andreas Aubert, Viggo Axelsen, Gregers Gram, Henrik Hop, William Houlder, Max Manus, Martin Olsen, Arthur Pevik, Birger Rasmussen, Tor Stenersen, and Edvard Tallaksen. The British historian William Mackenzie called the Oslo Gang "the best group of saboteurs in Europe". After saboteur training in England in 1943, he became the contact for all SOE agents in eastern Norway and head of the Norwegian Independent Company 1 group in Oslo. This group performed several spectacular acts of sabotage; among them smuggling out plates for the printing of Norwegian kroner from the Norwegian Central Bank to the exiled government in London and blowing up the office for Norwegian forced labour, thereby stopping the Nazis' plan of sending young Norwegian men to the Eastern Front. Sønsteby's gang also carried out the "Mardonius" action, blowing up several ships in Oslo harbour in April 1943. They also attacked Kongsberg munitions factory in September 1944, destroying guns and vital machine tools. In addition, they killed several leading figures in the Occupation Forces, including the Nazi head of police in Norway, Karl Marthinsen. Other actions included the theft of 75,000 ration books, which allowed pressure to be placed on authorities, stopping a threatened cut in rations; the destruction of sulphuric acid manufacturing facilities in Lysaker; destroying or seriously damaging over 40 aircraft, and related equipment which were being repaired at a tram company depot in Korsvoll; destroying a railway locomotive which was under repair at Skabo; destroying a number of Bofors guns, a field gun and vital machine tools at the Kongsberg arms factory; and starting a large fire in an oil storage depot at Oslo harbour which destroyed large quantities of oil and other specialist lubricants. After D-Day, Sønsteby concentrated largely on bombing Norwegian railways, thereby keeping German reinforcements from being moved back to the front line. His team also sank the German transport ship Donau outside Drøbak in 1945. Operating in occupied territory, and being high on the Gestapo list of wanted men, Sønsteby became a master of disguise. He operated under 30 to 40 different names and identities, and the Germans did not acquire his real name until near the end of the