Editing Battle of the Atlantic (section)

===Growing American activity===
[[File:Convoy WS-12 en route to Cape Town, 1941.jpg|right|thumb|A [[SB2U Vindicator]] scout bomber from USS ''Ranger'' flies anti-submarine patrol over Convoy WS-12, en route to [[Cape Town]], 27 November 1941.  The convoy was one of many escorted by the US Navy on "[[Neutrality Patrol]]", before the US officially entered the war.]]

In June 1941, the British decided to provide convoy escort for the full length of the North Atlantic crossing. To this end, the Admiralty asked the Royal Canadian Navy on 23 May, to assume the responsibility for protecting convoys in the western zone and to establish the base for its escort force at [[St John's, Newfoundland and Labrador|St. John's]], Newfoundland. On 13 June 1941, Commodore [[Leonard W. Murray|Leonard Murray]], Royal Canadian Navy, assumed his post as Commodore Commanding [[Newfoundland Escort Force]], under the overall authority of the Commander-in-Chief, Western Approaches, at Liverpool. Six Canadian destroyers and 17&nbsp;corvettes, reinforced by seven destroyers, three sloops, and five corvettes of the Royal Navy, were assembled for duty in the force, which escorted the convoys from Canadian ports to Newfoundland and then on to a meeting point south of Iceland, where the British escort groups took over.

By 1941, the United States was taking an increasing part in the war, despite its nominal neutrality. In April 1941 President Roosevelt extended the [[Pan-American Security Zone]] east almost as far as Iceland. British forces occupied Iceland when Denmark fell to the Germans in 1940; the US was persuaded to provide forces to relieve British troops on the island. American warships began escorting Allied convoys in the western Atlantic as far as Iceland, and had several hostile encounters with U-boats.

In June 1941, the US realised the tropical Atlantic had become dangerous for unescorted American as well as British ships. On 21 May, {{SS|Robin Moor}}, an American vessel carrying no military supplies, was sunk by {{GS|U-69|1940|2}} {{convert|750|nmi|km}} west of [[Freetown, Sierra Leone]]. When news of the sinking reached the US, few shipping companies felt truly safe anywhere. As ''Time'' magazine noted in June 1941, "if such sinkings continue, U.S. ships bound for other places remote from fighting fronts, will be in danger. Henceforth the U.S. would either have to recall its ships from the ocean or enforce its right to the free use of the seas."{{sfn|Time}}

A [[Mid-Ocean Escort Force]] of British, Canadian, and American destroyers and corvettes was organised following the declaration of war by the United States in December 1941.

At the same time, the British were working on technical developments to address the German submarine superiority. Though these were British inventions, the critical technologies were provided freely to the US, which then renamed and manufactured them. Likewise, the US provided the British with Catalina flying boats and [[Consolidated B-24 Liberator|Liberator]] bombers that were important contributions to the war effort.