Operation Tabarin was the code name for a secret British expedition to the Antarctic during World War Two, operational 1943–46. Conducted by the Admiralty on behalf of the Colonial Office, its primary objective was to strengthen British claims to sovereignty of the British territory of the Falkland Islands Dependencies (FID), to which Argentina and Chile had made counter claims since the outbreak of war. This was done by establishing permanently occupied bases, carrying out administrative activities such as postal services and undertaking scientific research. The meteorological observations made aided Allied shipping in the South Atlantic Ocean.
Following Cabinet approval in January 1943, there was an intensive period of planning, recruitment and procurement, before the expedition left the UK in November 1943, led by Lieutenant-Commander James Marr. Two bases were established in early 1944 – firstly, Base B, at Deception Island, South Shetland Islands, and later the main base, Base A, at Port Lockroy, Wiencke Island. A variety of science and mapping work was carried out. 14 men over-wintered in 1944.
In the Antarctic summer of 1944/45, Captain Andrew Taylor became leader, following the resignation of Marr due to ill health. A base hut was built on Coronation Island, South Orkney Islands (Base C) but not occupied. Base D, Hope Bay, Trinity Peninsula, was established as the centre for the expedition’s second year. The resupply of the bases included men, supplies and equipment, together with 25 sledge dogs to extend field work on the mainland of the Antarctic Peninsula. A full programme of science and mapping was undertaken. 21 men over-wintered in 1945.
The expedition was relieved in March 1946 by members of the newly formed Falkland Islands Dependencies Survey (FIDS). FIDS had been established in July 1945, following the end of the War in Europe, to put the work started by Operation Tabarin on a permanent footing. In 1962 FIDS was re-named the British Antarctic Survey (BAS), following Britain's ratification of the Antarctic Treaty and the creation of British Antarctic Territory.
The importance and achievements of Operation Tabarin cannot be overemphasised. It established the first permanently occupied stations in the Antarctic and in commencing geology, biology and mapping, was the foundation for continuous British scientific research in Antarctica. The huskies provided the core of a British Antarctic husky population, used for survey journeys, that lasted for fifty years.
Following the outbreak of World War II, Allied shipping across the globe became vulnerable to attacks by German Navy commerce raiders and U-boats. The War also threatened to reignite the longstanding Falkland Islands sovereignty dispute with neutral Argentina.
The important trade routes round Cape Horn and the Cape of Good Hope made the waters of the South Atlantic Ocean a particular target, with a corresponding threat to the Falkland Islands and its Dependencies. In January 1941, the German cruiser Pinguin attacked the unarmed and unescorted Norwegian whaling fleet. Pinguin seized a haul of 20,320 tons of whale oil, one of the largest prizes seized by a commerce raider during the war.
In response, the British authorities sent the armed merchant cruiser Queen of Bermuda to patrol the area between South Georgia, the South Shetland Islands and Weddell Sea. On 5 March, Queen of Bermuda visited the abandoned Norwegian whaling station on Deception Island, destroying stocks of coal and oil, and associated equipment, to prevent them falling into enemy hands.
The entry of Japan into the war in December 1941 increased the threat, with fear that Japan might seek to seize the Falkland Islands as a base in the South Atlantic. The Islands' defences were minimal and approaches to the USA for support were unsuccessful, though endorsed by the British prime minister, Winston Churchill. 
In January 1942, Argentina's Comisión Nacional del Antártico dispatched the transport ARA Primero de Mayo to Deception Island, afterwards sailing to the Melchior Islands, Palmer Archipelago and Winter Island. Argentine flags were raised in these locations and all territories south of 60° S and between 25° W and 68.34° W were declared annexed.
On 28 January 1943, the Colonial Office proposed dispatching the armed merchant cruiser HMS Carnarvon Castle to Deception Island after it had falsely claimed that a German commerce raider had been spotted in the area. Although by then, the threat of German commerce raiders had largely subsided, the deliberate ruse was enacted in order to conceal Britain's intentions from the U.S. and counter Argentina's ambitions.
Upon reaching Deception Island, Carnarvon Castle replaced the Argentinian flag with the Union Jack and placed four British Crown Land signs. A month later Primero de Mayo returned and duly replaced the Union Jack with the Argentinian flag. It then became obvious to the British government that only physical presence could settle the matter.
Planning for Operation Bransfield began on 27 May 1943. Named after Antarctic explorer Edward Bransfield, it was quickly changed to Operation Tabarin (after Paris-based cabaret Bal Tabarin) so as not to reveal its objectives.
Polar experts Neil Mackintosh, James Wordie and Brian Roberts took up the planning of the endeavor. Experienced Scottish marine biologist and polar explorer Lieutenant James Marr was selected as the head of the expedition. Marr, now a Lieutenant Commander, flew to Iceland where he procured Norwegian sealer Veslekari which was assigned the name HMS Bransfield. Bransfield proved to be unsuitable for the expedition as its freshwater tanks suffered from leaks; the party therefore traveled on the troopship SS Highland Monarch. On 14 December, Highland Monarch departed from Avonmouth, making stops at Gibraltar and Montevideo before reaching Port Stanley. There, the expedition's members re-embarked into Fitzroy and William Scoresby.
At 11 a.m. on 3 February 1944, the expedition landed at Port Foster, Deception Island. Much to the relief of its members the expedition found no signs of Argentine presence in the port apart from a flag painted on a fuel tank. Orders had previously been issued to avoid confrontation with the Argentines and the Chileans at all cost. The decrepit whaling station was transformed into Base B, where Flett, Matheson, Smith, Layther, and Howkins were to continue their work. On 6 February, the remainder of the expedition set course for Hope Bay where Station A was to be established.
At 1 p.m. on 7 February, William Scoresby dropped anchor 50 yards (46 m) off Hope Bay. The following day Marr was informed that Fitzroy would not be able to proceed to Hope Bay as ice being blown into the area by easterly wind could potentially trap the ship. A plan to reload Fitzroy's cargo into Scoresby was discarded because of the latter's limited capacity. Abandoning Hope Bay on 10 February the two ships pushed south-west along Graham Land and to Port Lockroy once heavy fog lifted.
Although it was known as a safe harbor, Port Lockroy's location restricted the range of scientific activities that the team intended to perform due to the fact that Gerlache Strait rarely froze, thus limiting access to the mainland. The ensuing ennui posed the risk of causing the team members to experience cabin fever as was the case on the Belgian Antarctic Expedition. The cargo was unloaded at the site of the newly established Station A on Goudier Island.
The first stage of the construction of the main hut christened Bransfield House was completed on 17 February, allowing William Scoresby and Fitzroy to return to the Falklands. On 19 March, Station A was visited by William Scoresby, which brought John Blyth, a carpenter from the Falklands, who joined the team. On 23 March, the Port Lockroy Post Office began its operation, with Farrington acting as censor. Falkland Island stamps overprinted with the inscription "Graham Land, Dependency of" were used. A day earlier, four expedition members had planted a Union Jack and a British Crown Land sign on Cape Renard.
On 23 April, the Stanley Post Office burnt to the ground. With correspondence now passing through Montevideo, the expedition's existence came to be known to the outside world. Survey work began in early May with the collection of rock samples from the foot of Jabet Peak and Savoia Peak. Lamb collected lichen samples and conducted experiments on the accumulation of snow and subsequent thawing. Lamb discovered a number of lichen species, including Verrucaria serpuloides, the only known true marine lichen, thus making a considerable contribution to the taxonomy of Antarctic lichens.
Later on Lamb visited Station B collecting specimens of amphipoda, ctenophora, sea urchins, worms and sponges from the beaches and shallow waters of Deception Island. On 18 November, a sledging expedition was launched on Wiencke Island where bird and lichen specimens were gathered, the former for the needs of the British Museum.
List of Winterers 1944
Base A, Port Lockroy 
Base B, Deception Island 
On 6 December, William Scoresby returned to Station B bringing plants native to the Falklands and soil for Lamb to conduct a transplantation experiment, which ultimately failed due to low humidity and strong winds. On 3 February 1945, Fitzroy and the 550 ton sealer Eagle arrived at Port Lockroy, with Victor Russell and David James, Norman Bertram Marshall, Gordon Lockley, Frank White, Alan Reece, Thomas Donnachie and Norman Layther aboard. Stores, equipment and crew members destined for the erection of an unmanned Base E on Stonington Island moved into Eagle, others boarded William Scoresby and Fitzroy in order to build Station D on Hope Bay.
On 7 February, Marr resigned on account of poor health and later returned to the Falklands, with Taylor replacing him as expedition leader. Taylor abandoned the plan to build the Stonington Island station focusing his attention on Station D. On 13 February, Seal Point was selected as the most suitable location for Station D and the first steps for its erection were made, construction was completed on 20 March. On 23 February, a hut was built on Coronation Island to reinforce British claims to the area. Later on the British expedition paid the Argentine meteorological station on Laurie Island a courtesy visit.
A few fossil specimens were collected at Hope Bay in February, with systematic gathering of paleobotanical specimens from Mount Flora's shale beginning on 8 June. A sledging expedition from Hope was launched in August. On 29 December, the sledging party returned to Base D, having visited Vortex Island, Duse Bay, James Ross Island and numerous small islands in its vicinity.
The trip resulted in 250 kilograms (550 lb) of lichen, fossil and rock samples, meteorological and glaciological measurements as well as corrections to Otto Nordenskjöld's maps.
List of Winterers 1945
Base A, Port Lockroy 
Base B, Deception Island 
Base D, Hope Bay 
On 14 January 1946, William Scoresby, Fitzroy and 300-ton sealer Trepassey began evacuating the members of the expedition to the Falklands. On 11 February, those serving in the military boarded HMS Ajax (22), and the rest sailed home on Highland Monarch.
The end of World War II led to renewed interest in the Antarctic region. The United States refused to recognise any foreign territorial claims to Antarctica, initiating Operation Highjump. Argentina and Chile signed the Argentine-Chilean Agreement on Joint Defence of "Antarctic Rights", a defence agreement that envisioned potential military action over disputed Antarctic lands. Chile organized its First Chilean Antarctic Expedition in 1947–1948.
Among other accomplishments, it brought Chilean President Gabriel González Videla to inaugurate one of its bases personally, and he thereby became the first head of state to set foot on the continent.
Britain, on the other hand, continued the operation of the bases built during Operation Tabarin by transferring them to the newly established Falkland Islands Dependencies Survey. Operation Tabarin veterans Reece, White and Rusell remained at their bases and continued their work for the FIDS. Participants of Operation Tabarin were awarded the Polar Medal in 1953.
Port Lockroy made the first measurements of the ionosphere and the first recording of an atmospheric whistler (electronic waves). It was also a key monitoring site during the International Geophysical Year of 1957. Port Lockroy was designated a Historic Site or Monument (HSM 61) and is now a museum following a proposal by the United Kingdom to the Antarctic Treaty Consultative Meeting.