And then these wolves of the sea, travelling at thirty or forty knots, tore through the columns of wallowing river barges, crushing them, drowning them in their wash, or simply dragging them by their towing cables until they were capsized. Any surviving barges were raked with gunfire, shells and flame throwers until the sea was littered with burning wreckage. Men in the water were being wiped out systematically. The destroyers even sent up flares to light up the night, the better to prosecute their slaughter. There was no rescue tonight, no honour of the sea, no pity.

But while Fleet E died, D was spared. Perhaps it was true in the east too, the men muttered, Fleet B soaking it up to spare Fleet C. Perhaps, the men whispered, Fleets D and C would make it to their landing sites, around Eastbourne and Rye. At Brighton and Dover, the destinations for E and B, there would only be wreckage and bodies washed ashore on a tide frothing with blood.

In that case, Ernst thought, listening, appalled, those who landed alive must make these huge sacrifices count.

In the dark, with the water lapping and the tug engines labouring, surrounded by the boom and crash of the fighting planes and ships, Ernst lost his sense of time. He was startled to realise that dawn light was seeping into the sky.

And there ahead of him, a grey line sandwiched between a steel sky and an iron sea, was land. He saw prickles of light. It was 0615, already half an hour after dawn, and, after a softening-up bombardment, the lead echelons must already have landed, were already fighting and dying.

A drizzle started. The sky was murky, charcoal grey. It was 21 September, S-Day. This was England. He thought he could hear church bells ringing distantly, a beautiful nostalgic noise. Hitler had had all the bells in Germany melted down for munitions.

The sound of the tug engines died, and the barge drifted. At last, thought Ernst. It was two hours since his first glimpse of land. Since then they had run parallel to the shore, before finally turning and driving in.

The sound of the long battle raging along the coast was already huge. The men lay as low as they could, sheltered by the barge's reinforced walls. But Ernst risked raising his head and looked out over the barge's fortified flank, hoping for his first glimpse of Pevensey, his landing site.

There was a murky light now, and the coast was obscured by haze and drifting smoke. But it was chaos on land and on sea. Assault-troop barges like his own were sliding in towards the shore, jostling for a place to land. On the beach more craft were stranded by a tide that was already receding, the rubber boats and speedboats of the advanced detachments. The beach itself looked littered, as if by bits of seaweed, and it was striped by peculiar black bands that ran parallel to the shore. The invaders were under fire. Ernst saw a tower to his right, and the larger guns of a coastal battery were coughing somewhere to his left; shells hissed as they flew, and landed with crashing explosions, or threw water spouts spectacularly into the air. From the area directly ahead Ernst heard the bark of automatic arms fire, and he saw the bulky silhouettes of pillboxes, fire sparking from the slits drawn in their forbidding faces.

All this was screened by smoke and a spray of water thrown up by the shells. But it was clear that the coastal defences were not subdued by the advance troops, as they had been promised. The very pile-up of boats struggling to find a place to land proved that something had gone wrong, that the beach wasn't clearing as fast as it should.

The barge's unteroffizier turned in the grey light. He was younger than Ernst, but his left cheek was darkened by a huge livid scar, picked up somewhere during the Nazis' dash across Europe. 'All right, lads. Now, we've been over the drill often enough. The first echelon are clearing the beach. They'll cover us when we land, and in turn we'll need to cover the command companies. Then we'll organise into our assault companies, get off the damn beach and through the marshy rubbish further up, and then we'll be off into the hills before breakfast.' Even as he said this, everybody could see the plan made no sense. The unteroffizier was faced by rows of wide-eyed faces, many of them pale under their blacking. 'Right, check your lifebelt,' he said. This was a bulky item like a motor tyre you wore under your gear. Ernst had his tucked up under his armpits. 'Remember what the officers said. Don't stop for wounded. Somebody else will follow up for them. Your job is to advance. Don't forget that…'

A motor roared, and their barge, one of a group of four, ploughed forward once more. The tug that had brought them across the Channel had to stand out to sea; a smaller motor-boat was dragging them to land. Whether the plan was defunct or not made no difference. They were going in.

As they neared the beach the barge jostled with those around it, gathering in a throng as tight as in Boulogne harbour. But now they were coming into the range of the shell fire, and Ernst ducked down, into the cover of the barge's hull. The men were splashed with water thrown up by the detonations, and once by a hail of splinters from some smashed boat.

There were screams nearby, and a rip of metal. Ernst risked another glance. One of the barges in his group was ripped open and was tipping, spilling out its men. Its flank had snagged on a tangle of scaffolding jutting out of the water, revealed by the receding tide.

Shingle scraped, and Ernst's barge rocked. It was grounded. The bat-wing doors opened, and the ramp at the front of the boat was let down. The unteroffizier jumped up. 'Off! Off!-' The shot hit him in the mouth. The back of his head detonated, and his jaw hung down, flapping, as he tipped into the water.

The men ducked down again. But now some English machine-gunner got his range. The bullets stitched the length of the barge and through the bodies of men who cried out, one after another.

'Get out!' Ernst screamed. 'We're sitting ducks here.' He stood again, and men pressed behind him, trying to get off the barge. Ernst realised he would never get to the ramp. Without letting himself think about it, he rolled his body over the side of the barge and dropped into the water.

He was submerged in water a few feet deep. The water's own bubbling filled his ears. The sea was murky and cold, and the pack on his back, his boots, felt inordinately heavy. He could see others falling into the water around him, and one burly trooper almost landed on top of him. And he could see the bullets lancing into the water, creating trails like tiny diving birds. He thrashed, trying to find his footing. The pull of his lifebelt under his armpits helped him.

His head came up above the water, into air that was filled with shouting and the singing of bullets and the whistle of heavier shells. He thrust his hands beneath him, scraping them on the shingle, and at last got his feet under him and dragged himself up. Head down, hefting his rifle, he just ran forward. The going was hard, the stones slippery, the water dragging at every movement. There were bodies floating around him, some riddled by bullets, but some unmarked – men must be drowning as they tried to get off the boats. And he was cold, by God; that was something he hadn't anticipated.

At last the water shallowed, and he found himself crunching over slippery shingle. The beach was long and sloping. It looked an awfully long way to the pillboxes beyond the sea wall which still spat their spiteful fire. And the beach was already littered with men lying still where they had fallen, and by the wreckage of boats and barges.

Automatic fire hissed through the air. He threw himself flat. He landed heavily, his pack slamming between his shoulder blades like a punch.