Bank Street facade

Somerset Street facade

Here are a couple of photos of the building that housed the Canadian Army's Discrimination Unit from early 1943 to August of that year.The Discrimination Unit (DU) was established in 1942 to sort the communications intercepted by the Army's Special Wireless Stations and analyze the "to" and "from" addresses and other external features of Japanese army and air force communications. According to the, "Their work was chiefly the deriving of intelligence concerning the movement of Japanese troops in the Pacific area through a study of the preambles of military messages." Today we might call this work metadata analysis, but at the time it was known as Traffic Analysis, or T/A.Most of the Japanese messages received at the Discrimination Unit were subsequently relayed to the U.S. Army's Signal Security Agency, which had the facilities to break the Japanese encryption systems and read the messages' content. Some were also processed at the Examination Unit (XU), Canada's own code-breaking agency.When it was created in March 1942, the DU shared quarters with the XU in a house at 345 Laurier Avenue East, adjacent to Prime Minister Mackenzie King's residence. By the beginning of 1943, however, the two units had outgrown the space available in the house. As a result, the DU was moved to new offices at 283 Bank Street, at the northeast corner of Bank and Somerset, where it occupied some or all of the space used by the Gowling Business College. It's not clear what the Gowling Business College did at this point; by the end of 1943, however, newspaper ads show that it was again (or still) in operation at the Bank Street building.By that time, the DU had already decamped for a new location, the top floor of the La Salle Academy , a Catholic boys' school on Guigues Street at Sussex Drive. In August 1943, the Army DU, the nascent RCAF Discrimination Unit, and a group of RCN T/A personnel jointly occupied the Guigues Street facility, while the school continued to operate on the floors below. In November 1943 they were joined by a Joint Machine Unit operating IBM punched-card machines to assist the traffic analysts. The JMU also assisted the cryptanalysts at the XU.These units were later amalgamated with the Japanese section of the XU to form the Joint Discrimination Unit, which eventually evolved into Canada's postwar SIGINT organization, the CBNRC, now called CSE.As can be seen in the photographs above, the Bank Street building was a multi-use facility with retail spaces on the ground floor, offices or other commercial space on the second floor, and a hall used for public events on the top floor.Over the years it hosted a variety of businesses, including the Gowling Business College, a hardware store, a jewellers, a Chinese restaurant, Imperial Cleaners & Dyers, the offices of the British Canadian Industrial Company and the International Land and Lumber Company, an 18-hole miniature golf course, and the public events hall, known originally as Queen's Hall and later as Hollywood Garden.According to this article , the building was destroyed by fire in the mid-1960s.The site is now occupied by the Primecorp Building (275 Bank Street), which offers a similar mix of retail space and offices.