The Story of Cavity Magnetron No. 12: Invited Paper

In the summer of 1940, following the breakthrough work of John Randall and Harry Boot at the University of Birmingham earlier that year, cavity magnetron model E1189, serial no. 12 was assembled by Eric Megaw and his collaborators at GEC Laboratories in Wembley, UK. According to James Phinney Baxter III, Official Historian of the U.S. Office of Scientific Research and Development, "When the members of the Tizard Mission brought one to America in 1940, they carried the most valuable cargo ever brought to our shores." The complete story of Cavity Magnetron No. 12, from the circumstances that led to its assembly at GEC Laboratories in Wembley to its pivotal role in the changing the direction of North American radar efforts during the Second World War to its current home at Ingenium in Ottawa, is widely dispersed amongst both published and unpublished sources. Here we present the results of our efforts to survey those sources, resolve some of the minor contradictions between various accounts, and add value to one of the most important items in Ingenium's collection.