 The US did not have enough ships to cover all the gaps; the U-boats continued to operate freely during the Battle of the Caribbean and throughout the Gulf of Mexico (where they effectively closed several US ports) until July, when the British-loaned escorts began arriving.These included 24 armed anti-submarine trawlers crewed by the Royal Naval Patrol Service; many had previously been peacetime fishermen.On July 3, 1942, one of these trawlers, HMS "Le Tigre" proved her worth by picking up 31 survivors from the American merchant "Alexander Macomb".