By 1 June, with the arrival of a further 5,000 British troops of the 5th Infantry Brigade, the new British divisional commander, Major General Jeremy Moore RM, had sufficient force to start planning an offensive against Stanley.
Plans were drawn up for half the Welsh Guards to march light on the night of 2 June, whilst the Scots Guards and the second half of the Welsh Guards were to be ferried from San Carlos Water in the Landing Ship Logistics (LSL) Sir Tristram and the landing platform dock (LPD) Intrepid on the night of 5 June.
On the night of 11 June, after several days of painstaking reconnaissance and logistic build-up, British forces launched a brigade-sized night attack against the heavily defended ring of high ground surrounding Stanley. Units of 3 Commando Brigade, supported by naval gunfire from several Royal Navy ships, simultaneously attacked in the Battle of Mount Harriet, Battle of Two Sisters, and Battle of Mount Longdon.
The conflict lasted 74 days and ended with the Argentine surrender on 14 June, returning the islands to British control. In total, 649 Argentine military personnel, 255 British military personnel, and three Falkland Islanders died during the hostilities.
On 20 June, the British retook the South Sandwich Islands, which involved accepting the surrender of the Southern Thule Garrison at the Corbeta Uruguay base, and declared hostilities over. Argentina had established Corbeta Uruguay in 1976, but prior to 1982 the United Kingdom had contested the existence of the Argentine base only through diplomatic channels.
On June 20, 1982, Saddam announced that he wanted to sue for peace and proposed an immediate ceasefire and withdrawal from Iranian territory within two weeks. Khomeini responded by saying the war would not end until a new government was installed in Iraq and reparations paid. He proclaimed that Iran would invade Iraq and would not stop until the Ba'ath regime was replaced by an Islamic republic.