CU convoys

The CU convoys were a World War II series of fast trans-Atlantic convoys to the British Isles. The earliest convoys of the series were tankers sailing directly from petroleum refineries at Curaçao to the United Kingdom. Most convoys of the series assembled in New York City and included fast freighters and troopships, with tankers arriving from Aruba via TAG convoys to Guantánamo Bay and GN convoys from Guantánamo to New York.

Allied war materials had been transported from North America to the United Kingdom in HX convoys since 1939 and in slower SC convoys since 1940. These convoys were escorted by the Royal Navy and Royal Canadian Navy. The United States Navy provided a few escorts to HX and SC convoys from September 1941 through April 1943.

CU convoys were established as an emergency measure to maintain petroleum fuel reserves in the United Kingdom for continued strategic bombing of Europe following heavy tanker losses along the east coast of North America during the Second Happy Time. Modern tankers could travel faster than the 9-knot (17 km/h; 10 mph) HX convoys, and the CU convoys were continued as a very fast (14-knot (26 km/h; 16 mph)) convoy series along the HX convoy route. United States destroyer escorts provided anti-submarine screens for CU convoys because the Flower-class corvettes of the British and Canadian Mid-Ocean Escort Force were not fast enough to maneuver with these convoys.

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