'Regulation' was a British naval operation to locate, intercept and either capture or sink German blockade-runners in the Bay of Biscay (February/August 1943).

Initially conceived as 'FD' (iii), the operation was based on the use of cruisers of Admiral Sir John Tovey’s Home Fleet, or alternatively cruisers which had just completed their working-up at Scapa Flow in the Orkney islands group before proceeding to overseas commands. After the arrival in Plymouth of any cruiser committed to 'Regulation', Admiral Sir Charles Forbes, the commander-in-chief Plymouth, assumed overall control of the operation, in which it was planned to maintain at least one cruiser on patrol, or at Plymouth ready to proceed at short notice, as long as the Germans continued their efforts to run the British blockade.

The light cruiser Jamaica was the first ship involved in the operation, and departed Scapa Flow on 1 February to proceed directly to the Bay of Biscay. Here the cruiser remained on patrol until 10 February when she reached Gibraltar to refuel after sighting nothing. The cruiser’s departure from Gibraltar was delayed by fuel contamination, but she left on 13 February to undertake a sweep to the north and then to the west. The cruiser remained in the Bay of Biscay area until 24 February and then proceeded to Scapa Flow, which she reached on 26 February.

The heavy cruiser Sussex departed Scapa Flow for the Clyde on 20 February, and after putting into the Clyde on 21 February steamed to the Bay of Biscay, which she reached on 24 February. Two days later a US Consolidated Liberator long-range maritime reconnaissance bomber operating from Plymouth reported a German tanker some 300 miles (485 km) to the west-south-west of Cape Finisterre on course toward a port in German-occupied France. The aeroplane continued to shadow the 7,982-ton Hohenfriedberg (previously the Norwegian Herborg captured by the raider Thor) until Sussex arrived during the afternoon and sank the ship with gunfire before avoiding a salvo of four torpedoes fired at her by U-264, which had been with the tanker. Sussex then proceeded to Freetown, Sierra Leone, to serve as the ocean escort for the WS.27 convoy to the Cape of Good Hope, and then to join the Eastern Fleet.

'Regulation' continued into March, April, May, June, July and August, when no interceptions were effected. The ships involved in this period were, in March, the light cruisers Kenya on passage to join Eastern Fleet, light cruiser Newfoundland afterward joining the Mediterranean Fleet, light cruiser Uganda on passage to the West Africa Station, and light anti-aircraft cruiser Charybdis, as well as the destroyers Matchless, Milne, Meteor, Musketeer, and Free Polish Orkan and Piorun; in April, the light cruiser Bermuda and light anti-aircraft cruiser Charybdis, as well as the destroyers Matchless, Meteor and Free Polish Orkan and Piorun; in May the light cruiser Glasgow and light anti-aircraft cruisers Charybdis and Scylla, together with the Free Polish destroyers Orkan and Piorun; in June the cruisers Bermuda, Charybdis and Scylla, as well as the Canadian destroyer Iroquois and Free Polish destroyer Orkan; in July the cruisers Bermuda, Charybdis on transfer to Gibraltar, Glasgow, Scylla on transfer to Gibraltar, and Sheffield, as well as the Canadian destroyers Athabaskan and Iroquois, and Free Polish destroyer Orkan; and in August the light cruisers Bermuda, Glasgow and Sheffield, as well as the destroyers Grenville and Canadian Athabaskan.