As Russell Pickett, 94, from Tennessee, was helped to his feet by the French president and hugged by Donald Trump, the 15,000 people gathered at the American cemetery in Normandy to commemorate the D-day landings 75 years ago stood to applaud.

“A tough guy,” the US president said, gesturing to the sole survivor of Company A of the 116th Infantry Regiment, 29th Division, which led the charge 75 years ago on to Omaha beach, a chaotic bloodbath which became known as the “suicide wave”and was made infamous by the Hollywood film Saving Private Ryan.

Pickett’s highly-trained company suffered a 96% casualty rate during the first hour on Omaha, the fiercest and costliest strip of beach landed during Operation Overlord, the world’s largest amphibious operation which would eventually pave a bloody way to the liberation of Europe.

The US air force’s bombing campaign had, unknown to the supreme allied commander General Dwight Eisenhower, failed to knock out the German defences ahead of the landing. This left the 29th division to emerge from the sea into untrammelled machine gun and artillery fire which turned the sand red and the sea into a gruesome soup of body parts.

Two thirds of Private first class Pickett’s company were to die within a week of the landing on 6 June 1944.

“It is difficult to explain how I feel about today,” Pickett told the Guardian once Trump’s Marine One had flown off and the TV cameras and military top brass had long gone from the cemetery’s 70 hectares (172 acres) of landscaped lawns overlooking Omaha beach close to the village of Colleville-sur-Mer.

Quick Guide What happened on D-day? Show What was D-day? D-day was an invasion of France by allied forces. It was codenamed Operation Neptune, and it aimed to push Nazi Germany out of occupied France. Five beaches in Normandy, codenamed Omaha, Utah, Juno, Sword and Gold, were the main targets for landing a large number of troops by sea. At 10pm on 5 June 1944, troops began departing from British shores to head across the Channel. Five assault groups set sail under darkness in an armada of about 7,000 vessels. Just after midnight on 6 June, aerial bombardment of enemy positions on the Normandy coast began. Special operations troops were also parachuted into France. US troops landed on Omaha and Utah beaches at about 6:30am. About an hour later Canadian forces landed at Juno, and British troops landed at Gold and Sword. Soldiers had to get off their boats, wade through the water, and seize control of the beach, all the while under heavy and sustained fire from German defensive positions. How was the plan kept secret? Despite involving a large number of troops, keeping D-day secret was vital to the success of the operation. A disinformation campaign had led the Germans to believe that Operation Fortitude was the main plan for the allies to invade the continent, via a two-pronged attack involving Norway and Calais. Even once the D-day landings had begun, German commanders were convinced they were just a diversionary tactic before the real invasion. Why is it called D-day? The D in D-day actually has no particular significance to Operation Neptune. It was common practice in the military to make plans that used the term, where the D stands for the day when operations commenced. Military planners also set H-hour, the time at which a plan was to begin. What happened next? By the end of the day, the allies had disembarked more than 135,000 men and 10,000 vehicles on to the beaches, and established bridgeheads of varying depths along the Normandy coastline. This came at the cost of 4,400 allied troops being killed, with thousands more injured or missing. There were also heavy casualties among German troops and French civilians. By 19 August, the allied forces had pushed down far enough to begin the battle to liberate Paris. German troops surrendered the French capital on 25 August 1944, two and a half months after D-day. Martin Belam

The night before the commemorative event where Pickett was to be garlanded by Trump and French president Emmanuel Macron, the veteran, who had no idea of what was planned, had spoken of his hopes that the business of the day would keep his mind busy.

“But, yeah, I had the flashbacks. I saw things today,” said Pickett, one of 16 veterans brought to Normandy by the Best Defense Foundation. “It was when I could see the beach from the cemetery. I could see my landing craft being hit as we got to the beach. But I have learned to live with it.”

Pickett was Company A’s flamethrower, a job he had been transferred to after witnessing a comrade being blown in half by TNT during his training in the demolition unit. “I wanted out of that. ‘You can be the flamethrower then,’ they said.”

His job at 6.30am on 6 June 1944 was to land on the beach, crawl through a gap made by the wire-cutters and run across the 300 metres of fine sand to knock out a German pillbox containing machine gunners.

His boat was in the lead in the assault on the beach.

But as Pickett’s landing craft came up to shore at the right time and in the right place, it hit something, possibly a mine or an artillery shell. “It just knocked me coo-coo,” said Pickett. The young soldier awoke sometime later in shallow water unable to move.

Aerial view of Omaha beach, Normandy. Photograph: Carlos Barría/Reuters

“About 12 to 15 feet to my right up in front there was a dead man and I couldn’t see his face and I don’t know who it was. And I couldn’t pull myself over there to see because my elbows were just digging into the sand.”

“I saw a lot – too much,” Pickett said. “A lieutenant on another boat, a big lieutenant, he had been a football player, we thought the world of him, Lt Fergusson. Well, I saw him running down the beach screaming and hollering: ‘I can’t see, I can’t see.’ His whole forehead was down over his face. You couldn’t see his face. He didn’t run far when another guy hollered at him to stop, and told him to turn directly to the left, off the beach. He did, he ran a few yards, and he was shot down.”

Pickett let the tide take him away from the beach where a landing craft was able to pick him up to be returned to England. “I kept on feeling my back for blood but there was nothing. Perhaps I was so terrified that my back and legs seized.

“By the time I got back to England I could hop around. They offered for me to go to hospital but they were saying how much they needed us back there. Another guy and I went back. Limping really. I was back with the company in six days.”

Pickett joined a unit seeking to liberate Saint-Lô. He was hit by grenade shrapnel in his left arm and sent back to England for 21 days – before rejoining the front again during the battle for the French port of Brest, where he was in a foxhole when an enemy shell collapsed a wall on top of him and left him on the edge of the death.

Pickett said he had been tormented over being unable to clear out the German machine gunners’ post on D-day. “I get gripey with myself on that. I go over it a lot in my mind. How many could have been saved? But then did I want to be the person to use the flamethrower? There were five men in there.”

Pickett’s nights and days have ever since been tortured by visions of what he saw. “But if it came to it – and I was involved – I would do it again,” he said. “I thought my country was worth it then and I still do.”