Keeping an Eye on the Americas: Canadian Wartime Signals Intelligence, 1939-1941

"W/T Room Interior - [No. 4 Wireless School Burtch]," November 13, 1941. Credit: Canada. Dept. of National Defence / Library and Archives Canada / Box [1996-212 NPC] 107

In summer 1939, the world was teetering on the edge of war. Localized conflicts on two continents threatened to bring about a second devastating global war. In September of 1939, Canada made the heavy decision to go to war alongside its ally, Britain, following the German invasion of Poland. The fascist Nazis could not be allowed to seize more territory in Europe—no one knew when Hitler’s appetite for territorial gains would be satisfied, if ever. After declaring war on Germany, Canadians immediately threw themselves into preparation for war. For years, Canadian and British convoys traversed the deadly submarine-infested Atlantic Ocean, keeping supply lines open to fuel the fight against Nazi aggression.

One important but rarely mentioned contribution which Canada made to the war effort in the early stages of the war came in the form of intelligence. This briefing book discusses the Canadian contribution of signals intelligence from 1939-1941, which came primarily from the interception of wireless communications. During these years, the United States remained neutral. In 1939, Britain assigned the Canadian military hemispheric responsibilities when it came to signals intelligence. Canada’s signals intelligence mission for the next two years would be the surveillance of wireless communications across the Americas—radio transmissions coming from, destined for, or passing over North and South America came under Canadian scrutiny.

Before 1939, there had never been such a large-scale wireless intelligence collection effort in Canada. Many parts of this Canadian intelligence system had to be constructed from scratch and built up over time. How did Canadian Military Intelligence quickly build up technological and specialized expertise in wireless interception from 1939 to 1941, and what were the challenges the Canadians came across when faced with this extremely ambitious project? At the outset of the war, Military Intelligence had only one wireless monitoring station, Rockcliffe (Ottawa), and no direction finding stations—for locating the source of a wireless transmission—other than those run by the Navy (which were mostly reserved for urgent and operational Navy use, not for general intelligence collection). By the end of the war, there would be several “Special Wireless Stations” run by Military Intelligence, dedicated to signals intelligence collection, and a whole infrastructure of translators, codebreakers, and other specialists dedicated to processing and analyzing the intercepted communications.

Over the two years that are the subject of this briefing book, we see Canada grow from a convenient geographic location where wireless communications inaccessible to British intelligence could be intercepted and forwarded to London, to an intelligence hub in its own right. Canadians sought to quickly do away with the guard rails put on Canadian intelligence by the British War Office, and in a very short time, the Canadians began to use the intelligence they collected for their own purposes, forwarding messages not only to London but to the Canadian Department of External Affairs and other Canadian government departments. The Canadian desire for increased independence and to use intelligence for Canadian interests shows through in the words and actions of Canadian intelligence officers.

Canadian signals intelligence relationships in this period were far closer with the U.K. than with the United States. This dynamic would change after the U.S. entered the war at the end of 1941, and the U.S. sought to take on more of a leadership role in Allied intelligence networks (especially from 1943 onwards). From 1939 to 1941, however, neither Britain nor Canada could necessarily count on military support from the U.S. to defend Europe and Britain from the growing threat of Nazi Germany. There was no defensive military alliance binding these three states. While from the second half of the twentieth century into the start of the twenty-first century, Canada’s closest military and intelligence cooperation would be with the United States, during the first half of the Second World War, Canada cooperated far more with the U.K.

This collection of documents shows us not only how Canada conducted signals intelligence during the war, but also how Canadians built signals intelligence sharing relationships with their counterparts in the U.K., the U.S., and later on with Australians as well. It is important to study the relationships that grew out of the Second World War to understand the intelligence sharing agreements that were made in the years after the war between Canada, the U.K., the U.S., Australia, and New Zealand. Wartime signals intelligence forever changed the way Canada saw the world and acted in it, as Canadian signals intelligence work and international intelligence cooperation continued even after victory in 1945.

For the Canadians who worked in wireless interception and intelligence during the war, Germany was not so far away as it was for most Canadians from 1939 to 1941. Wireless communications technologies fundamentally changed both war and intelligence, bringing the world closer together and creating a new non-geographical domain over which states had to attempt to exercise sovereignty. German propaganda radio broadcasts could not be prevented from entering Canada’s borders. But even as wireless technologies undermined geographic borders, they also created new opportunities for intelligence collection on a global scale. Because of the war, Canada got in on the ground floor of these advances in the field of wireless communications interception for intelligence collection. From 1939 to 1941, Canadian intelligence personnel were in direct competition with their enemies, long before a front in Western Europe was opened against the Nazis. In this way, one might count the intangible domain of radio communications as a frontline of the war for Canada in this early period.