The Greenland Patrol was a United States Coast Guard operation during World War II. The patrol was formed to support the U.S. Army building aerodrome facilities in Greenland for ferrying aircraft to the British Isles, and to defend Greenland with special attention to preventing German operations in the northeast. Coast Guard cutters were assisted by aircraft and dog sled teams patrolling the Greenland coast for Axis military activities. The patrol escorted Allied shipping to and from Greenland, built navigation and communication facilities, and provided rescue and weather ship services in the area from 1941 through 1945.
Earth's atmospheric circulation pattern requires westerly meteorological observations for prediction of weather conditions to the east. Weather observation stations in Greenland improved the accuracy of weather forecasting for the Atlantic Ocean and northern Europe for tactical advantage in the battle of the Atlantic and European theatre of World War II. Greenland had been part of the Danish colonial empire since 1814. Greenland appeared relatively unprotected following German occupation of Denmark on 9 April 1940. The Allies of World War II became concerned about the possibility of Axis military bases on Greenland. The cryolite mine at Ivittuut was a strategically important source of flux for electrolysis of aluminum ores by the Hall–Héroult process for aircraft production.
United States Coast Guard personnel had acquired extensive experience in the waters around Greenland as part of their International Ice Patrol duties since 1915. Following negotiations with the Danish Minister to Washington, the United States opened a consulate at Nuuk; and the USCGC Comanche transported the first American Consul to Ivittuut in May 1940. The United States then agreed to sell armaments to Greenland; and fourteen Coast Guardsmen were discharged to act as civilian armed guards protecting the cryolite mine with a 3-inch (7.6 cm) gun offloaded from the USCGC Campbell. USCGC Duane conducted an air survey of Greenland's west coast in August 1940, while USCGC Northland cruised along Greenland's east coast searching for evidence of European military activity and compiling information for publication of a Greenland Pilot. On 17 March 1941 USCGC Cayuga sailed from Boston with the South Greenland Survey Expedition to locate and recommend sites for airfields, seaplane bases, radio stations, meteorological stations, and aids to navigation. Northland relieved Cuyuga on 17 May 1941 to continue the survey expedition after Cuyuga was turned over to the Royal Navy as HMS Totland.
The United States occupied Greenland on 9 April 1941 under the expansive doctrine adopted at the Havana Conference (1940). As the survey results became available, construction began on a radio and aerological station on Akia Island and airfields at Narsarsuaq and at Kipisako near Ivittuut. Narsarsuaq Air Base was code-named Bluie West 1 (or BW1), and became the major Allied airfield in Greenland. Thousands of planes stopped there to refuel en route to England.
A South Greenland Patrol was established on 1 June 1941 with Geodetic Survey ship Bowdoin, tug USS Raritan, and cutters USCGC Comanche and USCGC Modoc. USS Bear with USCGC North Star and USCGC Northland established a Northeast Greenland Patrol a month later. The two patrols were consolidated in October 1941 as Task Force 24.8, the Greenland Patrol of the Atlantic Fleet.
On 12 September 1941 Northland intercepted the Norwegian sealer Buskø, which was supporting a German radio station transmitting weather information to Germany. Northland put a prize crew aboard Buskø, captured the radio station with some code information, and interned the personnel at Boston.
The Greenland Patrol was responsible for escorting ships bringing men and supplies to Greenland, and sometimes for breaking a path through the ice to assist their arrival. On 25 August 1942 USCGC Mojave was escorting the United States Army Transport Chatham as the fast section of convoy SG 6 while USCGC Mohawk and Algonquin were escorting the slow section of USS Laramie and Harjurand with steamships Biscaya, Arlyn and Alcoa Guard. Chatham and Arlyn were sunk by U-517 and Laramie was damaged by U-165.
Danes, Norwegians, and Inuit were recruited into a sledge patrol to search for additional Axis weather reporting stations along the coast. Sledge expeditions also rescued Allied airmen making forced landings on the Greenland ice cap. Coast Guard work parties built range lights, shore markers and LORAN radio beacons to aid navigation. Northland landed 41 men with thirty tons of equipment to establish a high-frequency direction finding station on Jan Mayen in November 1942.
The Greenland Patrol was augmented in the summer of 1942 by ten fishing trawlers purchased in Boston, repainted in blue and white Thayer system camouflage, and given Inuit names. Natsek disappeared on 17 December 1942 while transiting the Strait of Belle Isle with Nanok and Bluebird in gale force winds with blinding snow. The 116-foot (35 m) trawler was never seen again, and may have been capsized by ice accumulation from freezing spray in heavy seas. Surviving trawlers were returned to their civilian owners in 1944 as Tacoma-class frigates became available for weather ship duties.
SS Dorchester of convoy SG 19 was torpedoed by U-223 on 2 February 1943 while being escorted by USCGC Tampa, Escanaba and Comanche. Despite rescue efforts by the cutters, 675 men died of hypothermia or drowning in the worst United States troopship sinking of the war. Escanaba was later destroyed by a mysterious explosion on 13 June 1943.
From October 1943 Coast Guard Patrol Bombing Squadron Six operated twelve Consolidated PBY Catalinas from Narsarsuaq Air Base, Naval Station Argentia, and Reykjavík Airport providing reconnaissance, antisubmarine patrol, mail delivery, rescue service, and observation surveys of ice conditions for ships of the Greenland Patrol. Aircraft greatly improved patrol efficiency when weather conditions were suitable for flying. Ships of the Greenland Patrol acted as plane guards on weather patrol stations in the Davis Strait, Denmark Strait, and south of Cape Farewell maintaining radio contact with trans-Atlantic aircraft flights and provided rescue service for aircraft ditching at sea.
Between July and October 1944, Northland, Storis, Eastwind and Southwind captured sixty Germans while destroying Axis weather stations on the northeast coast of Greenland. The German weather ship Externsteine was captured and two similar ships destroyed in the course of this campaign which effectively ended Axis weather observation from Greenland.
Some ships of the Greenland Patrol were conventional cutters briefly assigned to the patrol. Others were unique and sometimes historic vessels specifically designed for polar exploration and well suited to conditions encountered by the patrol. Larger cutters escorted SG convoys of freighters and troopships between Sydney and the larger Greenland ports serving Narsarsuaq Air Base and the Ivittuut cryolite mine, while trawlers and tugs (sometimes towing barges) distributed supplies from those ports to smaller Army Bluie bases on remote fjords without port facilities.