A century of Canadian SIGINT
The Communications Security Establishment recently celebrated its 70th birthday, but Canada's SIGINT history began well before September 1946.
As I've mentioned before, Canadian SIGINT activities during the Second World War laid the foundations for Canada's participation in the post-war Five Eyes SIGINT alliance. But WWII wasn't the beginning of the story either.
In fact, the first recorded Canadian SIGINT activity took place on or about the 1st of January 1917, exactly one century ago.
According to Major Rob Martin (Cracking the Code, Winter 2004),
the earliest record of Canadian Corps intercept of German communications—predominantly telephone (non-wireless)—occurred about 1 January 1917, at "No 6 Post", Neuville St. VaastRegular monitoring of German radio communications began later in 1917 and continued until at least August 1918.
At demobilization, however, the fledgling wireless intercept elements suffered the same fate as many other Canadian Expeditionary Force (C.E.F.) wartime establishments—they were struck off strength—and no effort was made to create or sustain any organic Canadian Army capability in wireless intelligence, strategic or tactical, until the spring of 1938...
[Update 17 January 2017: Oops, judging from the comment below, 1917 may have been the start of army SIGINT activities, but Canadian naval SIGINT activities began shortly after the beginning of the First World War.]