To extend the range of their escorts, the United Kingdom occupied Iceland and Canadian-based escorts extended their coverage to the edge of the Grand Banks off Newfoundland. By May 1941, the gap had been closed to roughly . However, the U-boats continued to attack just beyond the range of the escorts, forcing the Allies to cover the gap. By this point three merchant ships were being sunk for every one being built and eight U-boats were being launched for every one that was sunk.