This is a timeline for the Battle of the Atlantic (1939–1945) in World War II. 1939 August August 19, 1939 Five U-boats sail from Kiel and nine from Wilhelmshaven to take waiting positions in the North Atlantic. August 21, 1939 German "pocket battleship" sails from Wilhelmshaven for a South Atlantic cruise. August 24, 1939 German "pocket battleship" sails from Wilhelmshaven for a North Atlantic cruise. September September 3, 1939 sinks the . 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 stops, evacuates and sinks the German freighter Inn off the Canary Islands. September 7, 1939 The first convoys sail outbound from the British Isles: OA from the English Channel, OB from Liverpool, and OG to Gibraltar. September 14, 1939 The first of the SL convoys sails from Freetown. attacks the British aircraft carrier , 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 and to an Atlantic rendezvous with Royal Navy ships and . September 17, 1939 sinks the Royal Navy aircraft carrier . September 17, 1939 The first Allied "fast convoy" HXF 1 sets sail from Halifax escorted by HMCS Fraser formerly . September 20, 1939 is sunk with depth charges from the British destroyers and . September 26, 1939 German media reports the sinking of the British aircraft carrier . However, this report is false: many such reports would be made during the war. September 30, 1939 German "pocket battleship" 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 October 5, 1939 German "pocket battleship" sinks the first merchant ship of its cruise. October 14, 1939 , under Kapitänleutnant Günther Prien, penetrates the British naval base at Scapa Flow, sinking at anchor. October 16, 1939