XU was the largest and most important intelligence organisation in occupied Norway during WWII. Most of the work of XU was kept secret until 1988.
XU was established in July 1940 by Arvid Storsveen, and was originally based on recruiting students from the University of Oslo. The group connected to professionals around Norway, within railroads, police and so on, and collected maps and photos of German fortifications and forces.
After a period of cooperation with Milorg, XU worked separately from the rest of the Norwegian resistance movement from the Autumn of 1941. This step was taken to increase the security.
Having established a network over the entire southern Norway,
Gestapo became aware of XU in the Spring of 1942. Several members of the leadership in Oslo, including Storsveen, fled to neutral Sweden in July 1942, and led the organisation from abroad. They still made occasional trips to occupied territory, and Storsveen was killed in a Gestapo operation in Oslo in April of 1943. He did not reveal who he was, and XU continued its work under the leadership of Øistein Strømnæs and Anne-Sofie Østvedt.
Strømnæs continued leading XU from occupied Oslo for the rest of the war. Apart from supplying the allied forces with very detailed data about the state of German forces in Norway, XU also had connections within Nazi Germany. Several of their members were couriers for MI5 agent Paul Rosbaud who had vital information regarding German nuclear research.
By the end of the war XU had some 1.500 agents all over Norway and had developed a sophisticated courier system to UK throught neutral Sweden. The amount of information could amount to some 500 A4 pages supplied every day. The amount of accurate intelligence meant that the allied forces had detailed information about most everything the German forces in Norway did and possessed. This information proved vital in bombing raids of strategic importance, and would have been invalueable if an invasion had been necessary.
