ON Monday, April 12, 1982, Britain’s 200-mile military exclusion zone around the Falkland Islands came into force – spelling out to Argentina where their warships and planes could be attacked.
The zone was designed to prevent Argentine reinforcements and supplies reaching the Islands from the mainland.
Meanwhile, the British submarine HMS Spartan arrived in the South Atlantic.
US Secretary of State Alexander Haig returned to London to continue peace talks. In a cable to President Reagan, Mr Haig said: ‘We cannot count on Mrs Thatcher to hold her fire as our diplomacy proceeds.’