In 1965, the 2nd Battalion, Parachute Regiment, was sent to Singapore for jungle training in response to the threat of invasion from Indonesian President Sukarno. By March, the battalion was established along the Malaysia–Indonesia border in Borneo and conducting 10-day patrols in the jungle. On 27 April, 'B' Company's base on the hilltop village of Plaman Mapu, consisting of company headquarters, a mortar section, and one weak platoon of young soldiers, was attacked by 150 Indonesians supported by rocket launchers, mortars, rifle grenades, and machine guns from the surrounding hills. The accurate fire caused several casualties amongst the defenders. The Company Sergeant Major (CSM), John Williams, was in command of the defence. He kept moving around the base, attending to the wounded, reorganising the defenders to counter each attack, and firing illumination rounds from a 2-inch mortar. The Indonesians penetrated the wire, taking out a mortar position. CSM Williams crossed the open ground under fire to man a machine gun, which he used to engage the Indonesians inside the perimeter. Covered by the machine gun, the Paras counter-attacked and forced the Indonesians back. The Indonesians had located CSM Williams's machine gun, and in a second attack, it was subjected to heavy fire at point-blank range. Wounded and blinded in one eye, CSM Williams returned fire, defeating the second attack. He then led a fighting patrol to attack two groups of Indonesians seen approaching the base.