'WG' was a British naval undertaking to intercept and capture or sink an eventual total of 10 German blockade-running ships in the Atlantic Ocean (February/March 1940).

In the first part of this effort, which involved a search for six German merchant ships which had broken out of Vigo in north-western Spain, search forces under the command of the commander-in-chief Western Approaches, Admiral Sir Martin Dunbar-Nasmith, were established using ships of the Home Fleet (battle-cruiser Renown, fleet carrier Ark Royal, light cruiser Galatea and a varying number of destroyers), of the Western Approaches Command, of the Northern Patrol and of the French Amiral-West command.

On 11 February the French sloop Elan captured the 2,542-ton Rostock and on the following day the British destroyer Hasty took the 4,709-ton Morea. The 4,709-ton Wahehe was is intercepted on 21 February in the area to the south of Iceland by the light cruiser Manchester and destroyer Kimberley of the Northern Patrol, but as a result of difficult weather and sea conditions Kimberley was unable to launch a boarding party until the following day and take the prize to Kirkwall in the Orkney islands group on 23 February.

After managing to break the Allied blockade, the 4,354-ton Orizaba was lost off Skjervøya in northern Norway after running aground, and the 7,768-ton Wangoni evaded the British submarine Triton off Kristiansand on 28 February and thus reached Kiel. The last ship, the 3,359-ton Arucas, was scuttled by her crew on 3 March when she was approached by the British heavy cruiser York to the east of Iceland.

Between 11 and 13 February, the 3,771-ton Wakama, homeward bound from from Rio de Janeiro in Brazil, was followed and then intercepted by the heavy cruiser Dorsetshire off Cabo Frio in Brazil, and was scuttled by her crew.

In the first days of March, in the western Atlantic, two German freighters (the 2,390-ton Troja and 6,530-ton Heidelberg) attempted to reach Germany from Aruba in the Netherlands West Indies. The former was encountered on 1 March by the light cruiser Despatch near Aruba and the latter on the following day by the cruiser light cruiser Dunedin off the Windward Passage, and their crews scuttled both the German ships.

Between 2 and 6 the heavy cruiser Berwick intercepted the 6,201-ton Wolfsburg in the Denmark Strait on 2/3 March and 5,846-ton Uruguay on 6 March. Their crews scuttled both of these German ships.

On 5/6 March three German freighters departed Curaçao in the Netherlands West Indies. The 7,305-ton Hannover was encountered in the Mona Passage during the night 7/8 March by the Canadian destroyer Assiniboine, and her crew were prevented from scuttling their ship inside Dominican waters by a boarding party from the light cruiser Dunedin. Hannover was later converted into Audacity, the first British escort carrier.

During the hunt for Hannover, in which the French light cruiser Jeanne d’Arc was also involved, the two other ships were able to break out of the Caribbean, but the 4,007-ton Mimi Horn was scuttled by her crew in the Denmark Strait on 28 March as the British armed merchant cruiser Transylvania approached her.

The 7,369-ton Seattle slipped through the Allied blockade and entered Tromsø in northern Norway, where she received permission from the neutral Norwegian authorities to sail around the Norwegian coast and into the Baltic Sea. Her last stop in Norway was Kristiansand. At dawn on 9 April, as 'Weserübung' began, the ship was on her way from Kristiansand when she came under fire from both German ships (the light cruiser Karlsruhe and others) and the Norwegian fortress of Odderøya, the latter believing that the ship was supply vessel supporting the German forces. Engaged by 150-mm (5.91-in) guns, the ship turned back toward Kristiansand, but was hit and caught fire. Her crew took to the lifeboats while the burning ship was abandoned. On landing, the members of the crew were held as prisoners of war until the following day. Seattle burned out for several days before starting to take in water and sank.

On 9 March the German transport ministry and naval high command issued instructions to German representatives overseas halting the departure of German merchant vessels as blockade runners until the autumn, but on 13 March in the Iceland-Færoes gap, the British armed merchant cruiser Maloja intercepted the 7,414-ton La Coruna, which had departed before the issue of the order, and the German crew thereupon scuttled their ship.