[3] After graduating from the Royal Military Academy, Sandhurst, Hamilton was commissioned as a subaltern with the Green Howards with the Service No.499793 in 1975, and served with the British Army in Cyprus, Belize, and South Armagh in Northern Ireland during Operation Banner.
[citation needed] Having survived two helicopter crashes in adverse weather conditions on the Fortuna Glacier in South Georgia during Operation Paraquet, two days later Hamilton led the advance elements of the forces which captured the main Argentine positions in Grytviken.
The next night his troop held off another enemy attack, in doing so enabling 42 Commando Royal Marines to fly in to reinforce the position on 31 May 1982, which was a key stage in the Falkland Islands campaign.
The patrol established itself in an observation post on the high ground of a ridge called Many Branch Point 2,750 yards (2,500 metres) from the Argentine positions, from which radio reports were dispatched.
Roy Fonseka, later a Seychellois cabinet minister) were manning the post when they were discovered by a four-man Argentinian patrol from the 1st Section of the 601 Commando Company, operating out of Port Howard.