Mount Harriet was one of the dark rocky peaks guarding the western approaches to Stanley, the Falklands capital, and taking it was part of a single brigade-sized night operation that also struck Two Sisters and Mount Longdon. Getting there had been an ordeal in itself. Lacking helicopters, the Royal Marines of 42 Commando, under Lieutenant Colonel Nick Vaux, had marched across the island through atrocious weather, some men carrying close to a hundred pounds. One corporal called it psychologically the hardest thing he had ever done: walking and falling, walking and falling, in cold and wet and exhaustion, on no sleep. For days before the assault, patrols probed the minefields and snipers harassed the defenders, denying them rest, while quietly searching for a way through to the south.

The plan turned on deception. As K and L Companies moved south around the mountain and across the mines to their start lines, J Company and supporting Welsh Guards launched a loud feint from the west, convincing the Argentines the blow was falling where they expected. K Company crossed first and climbed the slope undetected, slipping past sentries before the fighting began in earnest. A heavy naval and artillery bombardment, more than a thousand rounds, kept the defenders pinned and unable to take proper aim. The Marines worked their way through the rocks position by position. It was close, confused, dangerous work in the dark, and it was far from one-sided.

The defenders were conscripts and professionals of the 4th Infantry Regiment, and many of them fought hard. At one point a single Argentine machine-gun position, cleverly using a night-vision scope to make it seem a lone sniper held up the entire advance, drawing the Marines into a prepared ambush. Corporal Steve Newland broke it by charging the gun, knocking it out with grenades, and was shot through both legs for his trouble. The Argentine corporal who shot him was decorated for valor by his own country. After the war, British reporters tried to paint the defenders as hapless teenagers who folded at the first shot. A Royal Marine warrant officer who fought through the night corrected them flatly: the Argentines were good soldiers, better equipped with modern night sights than his own men, and they fought properly from start to finish.

By first light 42 Commando held the mountain, with more than 300 prisoners taken. Two Royal Marines were killed: Corporal Laurence Watts on Harriet itself, and Corporal Jeremy Smith on nearby Wall Mountain; about thirty more were wounded. Eighteen Argentines died defending the heights, counting the earlier patrol clashes and shelling. The battle had run longer than planned, leaving no time to push on and take Mount William in darkness. The dying was not quite finished, either: in the days after, a Welsh Guards messenger and a Gurkha engineer clearing the minefields were both killed by the explosives the defenders had left behind. Skill and surprise had carried the day, but the cost was paid in real lives on both sides of the wire.

What lingers about Mount Harriet is not only the tactics but what came afterward. In 2017, the British company commander David Wheen traveled to Argentina to meet Lautaro Jimenez-Corbalan, who had led a platoon on the mountain and was blinded by a booby trap as he withdrew. Wheen brought a painting of the battle; the Argentine veteran gave him his memoir of the 4th Regiment's war. Two years later, a Marine who had dragged a wounded Argentine NCO into cover during the fighting, and spent two hours tending him with sweets and cigarettes, tracked the man down and returned the helmet he had kept as a souvenir. Mountains taken by force, given back as gestures of peace: the men who fought each other here in the dark have spent the decades since learning to call one another by name.