The Battle of Mount Harriet was a military encounter between the British 42 Commando (Royal Marines), led by Lt Col Nick Vaux, and the Argentine Army’s 4th Infantry Regiment, under Lt Col Diego Soria, from June 11 to June 12, 1982, on Mount Harriet, East Falkland, about 10 miles from Port Stanley, during the Falklands War. The 4th Infantry Regiment, composed of 500 men, constituted part the occupation forces, which had deployed and dug in on Mount Harriet between April and May. The Royal Marines were the advancing and liberating forces, which had landed on the beach of San Carlos bay on May 21, initiating a long march eastward, toward Stanley, on the other side of East Falkland.
The Battle of Mount Harriet broke out with heavy naval artillery bombing on the Argentine positions, conducted with 113mm Mark 6 guns from the HMS Yarmouth (Type 12 frigate), and was followed by a night attack on Argentine mortar and machine gun nests, deeply engrained among the rocky outcrops of Mount Harriet, carried out by Royal Marines platoons, beefed up by Welsh Guards elements. The ferocious fighting lasted for several hours, with the British troops courageously charging up the slopes of Mount Harriet during the night to capture Argentine positions, ending the next morning, on June 12, with 68 Argentine casualties (18 KIA and 50 wounded) and 310 prisoners; the rest of the Argentine troops managed to escape during the night, heading back to Stanley.