After Germany invaded Russia, the U.K. and later the U.S. began providing materials to that country by convoy. The Arctic Convoys travelled from the U.K. and the U.S. to Archangel and Murmansk in northern Russia. These convoys faced the harshest weather conditions of the war. There were 78 convoys between August 1941 and May 1945 (although there were two gaps with no sailings between July and September 1942, and March and November 1943). About 1,400 merchant ships delivered vital supplies to the Soviet Union. 85 merchant vessels and 16 Royal Navy warships were lost. The Germans lost a number of vessels including one battleship and at least 30 u-boats as well as a large number of aircraft. No Coast Guard manned units participated in the Russian convoy route.
For a complete list of cutters engaged in the Battle of the Atlantic (North Atlantic and Malta) go to this Link.