Two British naval task forces (one of surface vessels and one of submarines) and the Argentine fleet were operating in the neighbourhood of the Falklands and soon came into conflict. The first naval loss was the World War II-vintage Argentine light cruiser ARA General Belgrano. The nuclear-powered submarine HMS Conqueror sank General Belgrano on 2 May. Three hundred and twenty-three members of General Belgrano’s crew died in the incident. Over 700 men were rescued from the open ocean despite cold seas and stormy weather. The losses from General Belgrano totalled nearly half of the Argentine deaths in the Falklands conflict and the loss of the ship hardened the stance of the Argentine government.
Regardless of controversies over the sinking, due to disagreement on the exact nature of the Maritime Exclusion Zone and whether General Belgrano had been returning to port at the time of the sinking, it had a crucial strategic effect: the elimination of the Argentine naval threat. After her loss, the entire Argentine fleet, with the exception of the conventional submarine ARA San Luis, returned to port and did not leave again during the fighting. The two escorting destroyers and the battle group centred on the aircraft carrier ARA Veinticinco de Mayo both withdrew from the area, ending the direct threat to the British fleet that their pincer movement had represented.
In a separate incident later that night, British forces engaged an Argentine patrol gunboat, the ARA Alferez Sobral, that was searching for the crew of the Argentine Air Force Canberra light bomber shot down on 1 May. Two Royal Navy Lynx helicopters fired four Sea Skua missiles at her. Badly damaged and with eight crew dead, Alferez Sobral managed to return to Puerto Deseado two days later. The Canberra’s crew were never found.