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This is a timeline for the Battle of the Atlantic (1939-1945) in World War II.



September 3, 1939

German submarine U-30 sinks the SS Athenia. This attack is interpreted by the United Kingdom as the start of unrestricted submarine warfare. However, in Germany it leads to stricter controls being issued by the Kriegsmarine. Germany at this point had 39 of its 58 U-boats at sea, but this was far less than the 300 which Admiral Karl Dönitz, chief of German submarine forces, considered to be necessary before the opening of war.

September 5, 1939

HMS Neptune stops, evacuates and sinks the German freighter Inn off the Canary Islands.

September 14, 1939

U-39 attacks the British aircraft carrier HMS Ark Royal, but fails to cause any damage. The aircraft carrier's escorts force U-39 to the surface with depth charges and the crew are taken prisoner.

September 16, 1939

The first Allied convoy sets sail from Halifax, Nova Scotia. Convoy HX 1 contains 18 merchant ships and is escorted by HMCS St. Laurent and HMCS Saguenay to an Atlantic rendezvous with Royal Navy ships HMS Berwick and HMS York.

September 17, 1939

German submarine U-29 sinks the Royal Navy aircraft carrier HMS Courageous.

September 17, 1939

The first Allied "fast convoy" HXF 1 sets sail from Halifax escorted by HMS Crescent.

September 20, 1939

U-27 is sunk with depth charges from the British destroyers HMS Fortune and HMS Forester.

September 26, 1939

German media reports the sinking of the British aircraft carrier HMS Ark Royal. However, this report is false: many such reports would be made during the war.

September 30, 1939

German "pocket battleship" Admiral Graf Spee sinks the first merchant ship of its cruise. Total sinkings for its sortie will total nine vessels of 50,000 tons before it becomes embroiled in the Battle of the River Plate.


October 14, 1939

U-47, under Kapitänleutnant Günther Prien, penetrates the British naval base at Scapa Flow, sinking HMS Royal Oak at anchor.

October 16, 1939

Germany begins employing magnetic mines. These cause significant losses to Allied shipping.


November 21, 1939

British light cruiser HMS Belfast hits a German mine, and is seriously damaged while operating in the Firth of Forth.

November 23, 1939

A German magnetic mine is recovered successfully by the Allies, leading to the development of effective countermeasures. The German battleship Scharnhorst sinks the British armed merchant vessel HMS Rawalpindi. The Scharnhorst and the accompanying Gneisenau are forced to abandon their sortie and return to port.


Dec 4

First U-boat lost to an Allied submarine in the war when HMS Salmon sank U-36 outside Kristiansund in Norway.

December 10, 1939

The first Allied troop convoy TC 1 sets sail from Halifax with 7,400 men of the 1st Canadian Infantry Division.



February 14, 1940

The United Kingdom announces armaments will be carried by all passenger ships. Germany responds by announcing that all vessels will be considered warships.


March 16, 1940

A German air raid at Scapa Flow damages a cruiser and causes the first civilian casualties in Britain of the war.


June 25, 1940

Canada loses its first navy vessel during an accident off the coast of France, when HMCS Fraser is cut in two by Royal Navy cruiser HMS Calcutta, with 45 lives lost aboard the Fraser and 19 aboard Calcutta.


August 4, 1940

U-52 sinks 3 British merchant steamships.

August 31, 1940

British destroyers HMS Esk and HMS Ivanhoe are sunk and two other ships damaged by mines in the Texel Disaster with the loss of 300 killed and 100 wounded or taken prisoner.


October 22, 1940

HMCS Margaree, recently acquired to replace HMCS Fraser, is sunk in a collision with the freighter MV Port Fairy 480 km west of Ireland. 142 men are lost, including the captain and four other officers.


December 1. 1940

HMCS Saguenay is the first Canadian naval vessel hit by torpedo in the Battle of the Atlantic, attacked 300 miles west of Ireland by a submarine while escorting Convoy HG 47.



May 21 or 22, 1941

Bismarck, Prinz Eugen, and three escorting destroyers leave Bergen and head toward the Arctic Ocean.

May 24, 1941

Bismarck and Prinz Eugen intercept the path of battleship HMS Prince of Wales and battlecruiser HMS Hood; Battle of Denmark Strait begins.
Bismarck sinks HMS Hood then badly damages Prince of Wales, forcing it to retreat.

May 27, 1941.

Bismarck sunk.


June 13, 1941

Newfoundland Escort Force is created under the command of Admiral Murray based at St John's Newfoundland, to provide escort cover from the coast of Canada to Iceland.


July 7, 1941

President Roosevelt announces that US warships will henceforth protect US merchant vessels in the North Atlantic, and the USA effectively joined the Battle of the Atlantic.


September 10, 1941

Canadian corvettes HMCS Moose Jaw and HMCS Chambly sink U-501 by depth charges and ramming in the Denmark Strait south of Tasiilaq, Greenland. This is Canada's first U-boat kill of the Battle of the Atlantic.

September 19, 1941

HMCS Levis is the first Canadian corvette sunk during the war. Levis is hit by a torpedo while escorting Convoy SC 44 off the coast of Greenland.


October 31, 1941

U-552 torpedoes USS Reuben James, which was escorting Convoy HX 156. Reuben James is the first United States warship sunk during World War II.



January 12, 1942

MV Cyclops is sunk 160 miles south of Halifax, heralding the start of a U-boat campaign that saw approximately 200 merchant vessels sunk within 10 miles of the east coast of the USA.

January 30, 1942

Convoy SC 67 departs from Halifax and picks up a transatlantic escort in Newfoundland, which accompanies the convoy as far as Northern Ireland. This marks the start of the allied end-to-end convoy escort system, which remained in effect until the end of the war.


February 16, 1942

Operation Neuland opens with attacks on Aruba, Curaçao and Lake Maracaibo petroleum facilities.[1]


March 20, 1942

A new system of BX and XB convoys is initiated between Halifax and Boston, to counter the U-boat campaign along the east coast of the USA.


June 10, 1942

U-553 torpedoes and sinks the British freighter Nicoya at the mouth of the St. Lawrence River several kilometres off Anticosti Island, followed by the Dutch freighter Leto


July 6, 1942

German submarine U-132 sinks three freighters off the Gaspé coast


September 14, 1942

HMCS Ottawa is torpedoed by U-91 while escorting Convoy ON 127 500 nautical miles (930 km) east of St. John's, Newfoundland. 114 crew lost their lives, including the commanding officer, while 65 survivors were rescued by nearby vessels.


October 14, 1942

Newfoundland Railway passenger ferry SS Caribou is torpedoed by the U-69, in Cabot Strait

October 24, 1942

A new system of UG convoys is initiated between Chesapeake Bay and the Mediterranean Sea, to support the Allied invasion of North Africa.[2]

October 25, 1942

Battle of convoy SL 125 begins as a tactical diversion to clear U-boats from the path of Operation Torch invasion convoys.[3]



February 15, 1943

A new system of fast CU convoys is initiated to speed the flow of petroleum products from Caribbean Sea refineries to Liverpool.[4]


May 6, 1943

The battle for convoy ONS 5 reaches a climax with the destruction of six U-boats.Rohwer, Jürgen; Hümmelchen, Gerhard (1992). Chronology of the War at Sea 1939-1945 (2nd ed.). Annapolis: Naval Institute Press. pp. 208&209. ISBN 1-55750-105-X. 


September 8, 1943

Italy surrenders, and Britain starts to redeploy their Mediterranean destroyers to the Atlantic.


December 26, 1943

Ships of the Royal Navy sink the German battleship Scharnhorst off Norway's North Cape.

Month-by-month summaries


  • September
Allied shipping losses total 53 vessels. 41 vessels totaling 153,800 tons are lost to submarines. German losses are two submarines.
  • October
Allied shipping losses total 196,000 tons. German losses are five submarines.
  • November
Allied shipping losses to submarines are 21 vessels totaling 51,600 tons. More than 100,000 tons are lost to German mines.
  • December
Allied shipping losses are 73 vessels totaling 189,900 tons. 25 are sunk by submarines. The Germans lose one submarine.

Total Allied losses to mines during 1939 are 79 vessels totaling 262,700 tons.


  • January
Allied losses are 73 vessels totaling 214,500 tons, of which 40 vessels totaling 111,200 tons are sunk by submarines. Germany has 38 operational submarines to begin the year.
  • February
Allied losses are 226,900 tons, of which 45 vessels totaling 169,500 tons are lost to submarines.
  • March
Allied losses are 45 vessels, of which 23 are lost to submarines. Germany loses three submarines.
  • October
Massacre of Convoy SC 7


  • June
Allied losses are 590,000 tons



  • March
Allied shipping losses are 627,000 tons.
  • April
Closing of Mid-Atlantic gap
  • May
Allied shipping losses are 157,000 tons, and 37 U-boats are sunk plus 32 damaged.
U-boats withdrawn Black May
  • June
17 U-boats destroyed
  • July
46 U-boats destroyed
  • August
20 U-boats destroyed


The Battle of the Atlantic by John Costello and Terry Hughes (1977, Collins, London) OCLC 464381083


  1. Kelshall, Gaylord T.M. (1994). The U-Boat War in the Caribbean. United States Naval Institute Press. pp. 26–33. ISBN 1-55750-452-0. 
  2. Hague, Arnold The Allied Convoy System 1939-1945 Naval Institute Press 2000 ISBN 1-55750-019-3 pp.179-183
  3. Edwards, Bernard (1999). Dönitz and the Wolf Packs. Brockhampton Press. pp. 115. ISBN 1-86019-927-5. 
  4. Hague, Arnold The Allied Convoy System 1939-1945 Naval Institute Press 2000 ISBN 1-55750-019-3 p.183

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