(HMCS Grilse, Canada's only actual submarine at the time of the Cuban Missile Crisis, was based in Esquimalt on the west coast. More about her in a subsequent post.)
At the height of the Crisis, from October 15th to 28th 1962, John F. Kennedy and Nikita Khrushchev were figuratively twisting wrists. The price of a misstep by either of them could have been a nuclear Armageddon. Rear-Admiral Ken Dyer sent his fleet to sea, to help monitor any Soviet submarines detected in eastern seaboard waters.
Besides his surface and air assets, Admiral Dyer had at his disposal two A-class boats of the 6th Submarine Flotilla, Alderney and Astute.
Alderney was followed by sister boat Astute into the cold north Atlantic waters. Neither A-boat would have positive submarine contacts during the crisis, but they demonstrated they were capable of forming part of an antisubmarine barrier. As things transpired, the Soviet submarines were already south of Canadian waters, where several were detected by American and Canadian forces.
On a personal note, I came to know the Alderney very well, as I trained in her and served on board only four years after her Cuban Missile Crisis service, in 1966-67.