<P> The year 1940 marked a change in attitude in the United States . The German victories in France, Poland and elsewhere, combined with the Battle of Britain, led many Americans to believe that the United States would be forced to fight soon . In March 1941, the Lend - Lease program began shipping money, munitions, and food to Britain, China, and (by that fall) the Soviet Union . </P> <P> By 1941 the United States was taking an active part in the war, despite its nominal neutrality . In spring U-boats began their "wolf - pack" tactics which threatened to sever the trans - Atlantic supply line; Roosevelt extended the Pan-American Security Zone east almost as far as Iceland . The US Navy's "neutrality patrols" were anything but, as in practice their function was to report Axis ship and submarine sightings to the British and Canadian navies, and from April the US Navy began escorting Allied convoys from Canada as far as the "Mid-Atlantic Meeting Point" (MOMP) south of Iceland, where they handed off to the RN . </P> <P> On 16 June 1941, after negotiation with Churchill, Roosevelt ordered the United States occupation of Iceland to replace the British invasion forces . On 22 June 1941, the US Navy sent Task Force 19 (TF 19) from Charleston, South Carolina to assemble at Argentia, Newfoundland . TF 19 included 25 warships and the 1st Provisional Marine Brigade of 194 officers and 3714 men from San Diego, California under the command of Brigadier General John Marston . Task Force 19 (TF 19) sailed from Argentia on 1 July . On 7 July, Britain persuaded the Althing to approve an American occupation force under a U.S. - Icelandic defense agreement, and TF 19 anchored off Reykjavík that evening . U.S. Marines commenced landing on 8 July, and disembarkation was completed on 12 July . On 6 August, the U.S. Navy established an air base at Reykjavík with the arrival of Patrol Squadron VP - 73 PBY Catalinas and VP - 74 PBM Mariners . U.S. Army personnel began arriving in Iceland in August, and the Marines had been transferred to the Pacific by March 1942 . Up to 40,000 U.S. military personnel were stationed on the island, outnumbering adult Icelandic men (at the time, Iceland had a population of about 120,000 .) The agreement was for the US military to remain until the end of the war (although the US military presence in Iceland remained through 2006, as postwar Iceland became a member of NATO). </P> <P> American warships escorting Allied convoys in the western Atlantic had several hostile encounters with U-boats . On 4 September, a German U-Boat attacked the destroyer USS Greer off Iceland . A week later Roosevelt ordered American warships to attack U-boats on sight . A U-boat shot up the USS Kearny as it escorted a British merchant convoy . The USS Reuben James was sunk by U-552 on 31 October 1941 . </P>

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