Epilogue: Radio as a Frontline of the Second World War for Canada

The United States enters the war

In December 1941, the Americans declared war on both Japan and Germany. For just over two years, Canada had been the sole North American country fighting this war, and Canadian intelligence had shouldered hemispheric responsibilities in the realm of wireless interception. With the entry of the extremely powerful United States, that period of the war came to an end. As we have seen in this briefing book, there was already some intelligence cooperation between the U.S. and the Allies before December 1941. So, what changed when the Americans officially entered the war?

From the documents in this collection, it is clear that from 1941-1945, Canadian intelligence cooperation with the U.S. increased drastically. At first, as the Americans began to set up their own wartime signals intelligence operations, they would frequently come to the Canadians and British for information on various radio stations. In one instance in March 1942, the U.S. F.C.C. became worried about the activities of certain South American stations, and asked for Canada’s assistance, since Canada had already been monitoring South American radio transmissions since early 1940 (CDWI00268). Over time, the Americans grew more confident in the field of signals intelligence, and began to take on more of a leadership role in the U.K.-U.S.-Canada intelligence sharing relationship—whereas from 1939-1941, Britain had undoubtedly been in charge of Allied intelligence efforts. The changes in this trilateral dynamic led Canada to develop closer ties to American intelligence, which remained after the end of the war in 1945. There are documents in this collection which show postwar signals intelligence cooperation between Canada and the U.S., but they are beyond the scope of this briefing book.

Although for two years, Canada’s primary signals intelligence mission had been keeping an eye on the Americas, once the U.S. joined the fight, the Americans began to inform the Canadians of their own monitoring of Canadian communications as well, constantly reporting to the Canadians anything strange they intercepted which they believed to have a Canadian origin. There are too many examples of these kind of interactions between Canadian and American intelligence to list here, but one instance (from May 1942) is shown by the documents in the table below.

In the early period of the war discussed in this briefing book, 1939-1941, Canada’s main point of contact for intelligence issues was Britain. Initially, Canada would intercept wireless transmissions and forward these ‘raw’ intercepts to the War Office in London. But this situation did not last. Canada began to develop more and more of its own independent signals intelligence capabilities, and grew to have more contact with American intelligence in addition to British intelligence. By 1943, these documents suggest that the U.K. was no longer the centre of a series of bilateral relationships with each of its dominions and allies, but that relationships began to form and strengthen between countries like Canada and the U.S. and Australia. In early 1943, the Canadian Department of External Affairs, Department of Transport, and Military Intelligence worked together to coordinate signals intelligence efforts in the Pacific with the “Australian Broadcasting Commission’s Shortwave Department” (CDWI00380 and CDWI00381). It made geographic sense for Canada to have closer cooperation on Pacific signals intelligence with the United States and Australia than with Britain in the later stages of the war.

Through the Second World War, Canada’s intelligence alliance grew from a simple bilateral relationship with the U.K. to a complex system of global cooperation across three continents— working with the U.K., the U.S., and Australia to achieve victory through unprecedented international intelligence cooperation.

In November 1943, Ottawa’s Psychological Warfare Committee turned its discussion to the German “Forces Family Letter Box” campaign against Britain. In these twice-weekly radio broadcasts to the U.K., messages from British soldiers and sometimes Canadian airmen (who flew with the R.A.F.) could be heard. Copies of these broadcasts were shared with Ottawa through Canada House in London (CDWI00382). Canadians from the Department of External Affairs and Military Intelligence were anxious to identify and tune in to a German broadcast featuring specifically Canadian prisoners of war, but by December 1943, they had still had no luck—although, strangely a German broadcast of this type directed at South Africa could be heard in Ottawa (CDWI00383). Had the Nazis given up on psychological warfare against Canada in particular by 1943? Ottawa couldn’t be sure.

In their search for German radio broadcasts directed at North America, Canadian Military Intelligence intercepted many such broadcasts featuring messages from American prisoners of war. Documents CDWI00384 to CDWI00395 are all broadcasts of messages from American prisoners of war in Germany from December 1943. You can access individual documents by seaching for specific CDWI identifiers (e.g., CDWI00386) on the search bar of this website.

This briefing book shows the importance the Canadian military attached to defending and monitoring wireless communications during the Second World War. The use of wireless technologies in warfare and intelligence was a new and quickly evolving field. An enemy an ocean away could potentially spy on Canadian communications, or reach Canadian audiences and spread propaganda, lies, and mistrust. While Canada was on the offensive with its signals intelligence mission during the war—intercepting enemy broadcasts and breaking foreign codes—wireless interception also had a defensive nature, as we saw in the counter-intelligence examples. And we cannot forget that at the same time Canadian Military Intelligence was targeting enemy communications, Canada’s enemies were trying to gain intelligence from intercepting Canadian communications as well.

During the war, Canada and its allies began to see the realm of wireless communications as a ground over which to gain or lose advantage in a global intelligence race. After the war, this mindset did not go away, and vestiges of the wartime wireless interception operations would make their way into the postwar world. The cat was out of the bag, so to speak, and the knowledge of how to spy on wireless communications globally was not something Canada—or any other major belligerent in the war—was willing to completely set aside, even in peacetime.