slow speed of SC convoys became so dangerous to the convoy system that in November, convoy SC 52 returned to Canada after it was intercepted by U-boat packs shortly after beginning its trans-Atlantic voyage. In mid-November the NEF gained respite as the Germans abandoned the North Atlantic and re-directed their efforts elsewhere. Merge into Mid-Ocean Escort Force By December 1941, 78% of the Royal Canadian Navy's strength was allocated to the NEF. With the entry of the United States into the war in an official capacity in December, command over the western Atlantic was altered. Initially there was a flood of United States Navy vessels into the Atlantic. However, with the conflict with Japan in the Pacific needing more escorts, the United States began withdrawing from the battle in the Atlantic. The US contribution further diminished after German attacks on shipping off the US East Coast and in the Caribbean Sea. Canadian warships were withdrawn from North Atlantic service and sent south to counter the threat. In January 1942, the NEF and British-based escorts were amalgamated into the new Mid-Ocean Escort Force command. In order to free up extra escorts to fill out American escort groups, Iceland was abandoned as a route point, with escorts instead beginning in Derry, Northern Ireland or sites in Newfoundland and sailing directly for the other. Citations References Escort Groups of the Royal Navy in World War II North Atlantic convoys of World War II American Theater of World War II Battle of the Atlantic History of Newfoundland and Labrador Royal Canadian Navy Military units and formations of Canada in World War II Naval battles and operations of World War II involving the United Kingdom