In May, King (by this time both Cominch and CNO) finally scraped together enough ships to institute a convoy system. This quickly led to the loss of seven U-boats. 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". Shortly after, "Le Tigre" managed to hunt down the U-boat that had torpedoed the merchant ship, which was then sunk by ; credit was awarded to "Le Tigre". The institution of an interlocking convoy system on the American coast and in the Caribbean Sea in mid-1942 resulted in an immediate drop in attacks in those areas. As a result of the increased coastal convoy escort system, the U-boats' attention was shifted back to the Atlantic convoys. For the Allies, the situation was serious but not critical throughout much of 1942.