The Beginning of Hostilities

[…] the tightening of the allies’ defence in the Western Atlantic between February and May 1942, persuaded [Grand-Admiral Karl] Dönitz to deploy his U-boats in less highly protected waters.
The U-boat campaign on the St. Lawrence began by chance, but would come to be of the highest importance, first of all for Canada and ultimately for German operations. […] U-boat U-533 was damaged by escorts south of Newfoundland in May, 1942. Serious mechanical failures added to the damage, Commander [Karl] Thurmann believed that he could not begin repair work whilst in the highly defended waters surrounding Halifax. As a result, he decided, rationally, to retreat to calmer waters in the Gulf of
St. Lawrence, which had just been freed of its winter covering of ice. This allowed him to ambush ships picking back up their activities in coastal waters. Shortly after midnight on May 12, Thurmann arrived off the northern coast of the Gaspé peninsular and quickly sunk two ships, the Nicoya and the Leto. These two vessels had left Montreal on May 10, one was headed towards Halifax and the other towards Sydney to join the trans-Atlantic convoys.

For more information on the Battle of the St. Lawrence::

W. A. B. Douglas et al., No Higher Purpose: The Official Operational History of the Royal Canadian Navy in The Second World War, 1939-1943, volume II, part I, St. Catherines, Vanwell Pub., 2002.

GREENFIELD, Nathan M., « La bataille que le Canada a choisi d’oublier », Magazine Gaspésie, vol. 40, no. 1, summer 2003, p. 29-30.

GREENFIELD, Nathan M., The Battle of the St. Lawrence, Scarborough, Harper Collins Publishers, 2004, 286 p.

HADLEY, Michael L., U-boats Against Canada: German Submarines in Canadian Waters, Kingston, Ont.: McGill-Queen’s University Press, c1985, 416 p.

HADLEY, Michael L., « La bataille du Saint-Laurent », Magazine Gaspésie, vol. 40, no. 1, summer 2003, p. 15-19.

SARTY, Roger, « Une défaite presque totale pour le Canada ? », Magazine Gaspésie, vol. 40, no. 1, summer 2003, p. 31-35.

SARTY, Roger, War in the St. Lawrence: The Forgotten U-Boat Battles on Canada’s Shores, Toronto, Allen Lane, 2012, 355 p.

TRÉPANIER, Louis, « 1942 : la Bataille du Saint-Laurent », Revue d’histoire du Bas Saint-Laurent, vol. 9, no. 3, October-December 1983, p. 85-96.

Battle of the St. Lawrence, https://en.wikipedia.org/wiki/Battle_of_the_St._Lawrence

Battle of the Gulf of St. Lawrence, http://www.veterans.gc.ca/eng/remembrance/history/second-world-war/battle-gulf-st-lawrence

The Summer of 1943: An Episode in the Battle of the St. Lawrence River – Surveillance, Defence and Propaganda, http://www.journal.forces.gc.ca/vo7/no1/history-histoire-01-fra.asp

Battle of the St. Lawrence, http://thecanadianencyclopedia.ca/en/article/battle-of-the-st-lawrence/

U-boat Operations, http://thecanadianencyclopedia.ca/en/article/u-boat-operations/

Photos of the Battle of the St. Lawrence, https://www.flickr.com/photos/museenavaldequebec/sets/72157623500309831/?page=4
You are now ready to experience first-hand the Battle of the St. Lawrence as it happened in Quebec. This animated reconstruction lifts the veil on a little-known episode of the Second World War.

Nicoya and Leto
May 11-12, 1942
U-553

Convoy QS-15 – Dinaric, Hainaut and Anatassios Pateras
July 5-6, 1942
U-132

Convoy QS-19 – Frederika Lensen
July 20, 1942
U-132

Convoy QS-33 – Aeas, HMCS Raccoon, Oakton, Mount Pindus and Mount Taygetus
September 6-7, 1942
U-165 and U-517

HMCS Charlottetown
September 11, 1942
U-517

Convoy QS-36 – Saturnus, Inger Elisabeth and Joannis
September 15-16, 1942
U-517 and U-165

Convoy NL 9 – Carolus
October 9, 1942
U-69