The carnage of the Warrenpoint bombing has been recalled by General Sir Mike Jackson, who later became the most senior soldier in Britain's armed forces.
His memoirs, to be published next week, reveal Sir Mike took command of the scene and still lives with the horrifying images he saw that day.
Eighteen of his comrades, including one of the most senior officers to die in the Troubles, were killed by twin IRA blasts.
The attack in August 1979 was the worst loss of life for the British Army in the Troubles and the worst single incident for the Parachute Regiment since Arnhem.
The general said he had never seen "carnage on this scale". He writes that he had to identify another officer, a close friend, by facial skin blown off his skull.
General Sir Mike Jackson was a major in the Paras when the attack happened on the same day Lord Mountbatten was murdered.
He had also been present at the Bloody Sunday killings and recently said he believed innocent people were shot by the Paras in 1972.
His 45 years in the Army culminated when he was made Chief of the General Staff in 2003. He relinquished the post last year.
In his book, Soldier, he says he was stationed at Bessbrook Mill - the army base that recently closed - when he heard about the double bomb attack.
An IRA bomb hidden in a hay trailer blew apart a Para convoy passing Narrow Water, outside Warrenpoint, around 4.30pm on August 27, 1979.
Soldiers opened fire at individuals across the water, believing they might be the bombers, and killed a tourist who worked for the Queen.
Minutes later a second bomb exploded at the entrance to Narrow Water Castle, where the IRA had correctly calculated that the Army would set up a command post. Lt Colonel David Blair, who had arrived at the scene by helicopter, and Major Peter Fursman were among those killed.
The then Major Jackson was sent to the scene and arrived to find he was the most senior officer present.
"I arrived at the incident within half an hour of the second explosion," he said. "As we circled before landing, I could see two craters and large scorch-marks on the road.
"It was a horrifying scene.
"There was human debris everywhere - in trees, on the grass verge and in the water.
"Mostly unidentifiable lumps of red flesh, but among them torsos, limbs, heads, hands and ears. I have seen the effect of bombs before but never carnage on this scale. All that was left of the driver of the rear lorry was his pelvis, welded to the seat by the intense heat."
General Sir Mike writes: "In such circumstances your emotions shut down and training takes over."
He added: "It stayed light late that warm summer evening. It seemed unbelievable that something so terrible could have happened in such a beautiful spot.
"One of the divers from the Royal Engineers asked me quietly to come and look at something he'd found in the water.
"It was a human face blown clear of the man's skull. The line of a moustache was still visible. The diver asked if I recognised the man. I felt a shiver of horror. 'Of course I do,' I said in a shaky voice. 'He's a good friend of mine.'"
The man was Major Fursman.
Another soldier, David Blair, was identified only by the crown and the star of his rank on his epaulette.
"I still have ugly pictures in my head from that terrible day. Once you've seen such appalling sights you can't close your mind to them," he writes.
Soldier by General Sir Mike Jackson is published by Transworld on September 10