Adding to the deception were two huge but imaginary military units. One, supposedly preparing to invade Norway, provided German radio interceptors with the busy radio traffic of a simulated 350,000-man army whose needs included "ski training" and "handbooks on engine functioning in low temperatures." A second phantom army appeared poised to strike at Calais under the command of Lt. Gen. George S. Patton. Spies tipped the Germans that Patton had arrived in England to lead the Calais invasion. Luftwaffe reconnaissance flights photographed the evidence of Patton's army: rows of tanks and barracks, fleets of landing craft in nearby ports, even an oil dock. All were illusions, made of wood, rubber, and papier-mâché by fakers who included movie stagehands.

An XX committee operative added her contribution by reporting to the Germans that she was dating a staff officer of the nonexistent U.S. Fourteenth Army, which had moved its headquarters to the Dover area, opposite Calais, to prepare the invasion. (So complete was the deception that Fourteenth Army shoulder patches appeared alongside real ones in a 1944 National Geographic booklet on U.S. armed forces insignia.)

But what about reports the Nazis were receiving of a Normandy invasion? That, said the Germans' most trusted spy (and XX's star performer) would only be a diversion. A message sent on June 9—and read by Hitler himself—warned that D-Day was a trap designed to draw off German reserves so that the Allies could launch a decisive attack, "probably . . . in the Pas de Calais area." The ruse would keep German forces in Calais for weeks after D-Day, awaiting the "real" invasion.

While the Germans built up their forces around Calais, Field Marshal Rommel placed the underwater obstacles at Normandy that the dicers had spotted. Rommel had asked in vain for more cement and mines for Normandy. Denied, he made do with obstacles of timber and steel. "Our only possible chance will be at the beaches," he said. If the invaders came to Normandy, he would stop them there. He expected them to come in on a high tide and impale their craft on his barriers.

By late May, Rommel's men were in their bunkers overlooking the Normandy beaches, wondering if the invaders would land there—or hundreds of miles (kilometers) away. At Widerstandsnest (strongpoint) 62, overlooking what would be Omaha Beach, German troops were listening to popular music on a windup gramophone and reading letters by candlelight.

Sgt. Valentin Lehrmann learned that he had just become a father for the third time. The baby, Elfriede, was born May 26. Nearby, Pfc. Hein Severloh, the son of a farmer and at 21 a veteran of the Russian Front, brooded about his fate: "I knew if I did not kill them, they would kill me. All I wanted was to get out of this hell. All I wanted was to survive."

Around the same time, invasion troops were pouring into sealed-off camouflaged camps on the English coast. At a camp in Weymouth the King and Queen of England paid a surprise visit that took them among men of the Sixth Naval Beach Battalion, Joe Vaghi's outfit. Someone in the queen's party handed 17-year-old sailor Clyde Whirty an American flag, which he attached to the bulldozer he was to use to clear paths on the Easy Red beachhead. When a buddy warned that the flag would draw German fire, Whirty, a thin, quiet-spoken man, shrugged and said, "If they kill me, they won't kill someone else."

On June 1 armed officer-messengers boarded the Allied vessels at the departure ports. Each commanding officer was handed a sealed envelope marked Top Secret. Inside was another sealed envelope. The Operation Neptune message inside revealed the date of D-Day: June 5, with a possible change to June 6 or 7. The message ended: "Destroy this by burning when you have read and understood."

The weather was stormy on June 5. The next day the sea was choppy but the storm had passed.

Soon after dawn on June 6, a fleet of Allied warships appeared in the steel gray fog off Normandy Beach and prepared to bombard the German fortifications detailed in the BIGOT map. Behind Utah Beach, German shore batteries fired first, some guns zeroing in on the U.S. destroyers Fitch and Corry. The ships were turning to starboard to line up parallel to the beach. They would then anchor to become steady gun platforms for the shore bombardment. At 6:10 a.m., exactly on schedule, Allied planes began laying smoke screens to hide the destroyers. But one of the planes was shot down before it could hide the Corry.

German guns immediately targeted the ship, which, while still firing, began twisting past plumes of near misses. Then, a little after 6:30, she struck a mine. Eight minutes later, with the main deck underwater and the Corry breaking in half, the captain, Lt. Comdr. George Dewey Hoffman, ordered his 18 officers and 265 men to abandon ship. When all the living were in the 54-degree water, Hoffman joined them. The shelling continued, and more men died while struggling in the cold sea. By the time rescuing destroyers appeared two hours later, firing at Germans from one side of the ship while saving men on the other, the Corry's 260 survivors were near death. All told, the Corry, which had fired off 400 rounds during her few minutes of D-Day, lost 24 men. Her flag, snatched from the sinking ship by Lt. Paul Garray, still survives.

At about 7:30, the Sixth Naval Beach Battalion began to land on Omaha Beach, at a site their BIGOT maps designated as Easy Red sector. Clyde Whirty's bulldozer, the American flag flying, rolled off a landing craft and hit a mine. Clyde grabbed the flag, jumped off the wreck, and headed for another bulldozer, whose driver had been shot in the head. Clyde removed the body and headed up the beach. Then an artillery shell smashed that bulldozer. Still clutching his flag, Clyde sprinted toward an abandoned bulldozer, got in, and drove off. By the end of the day, Clyde was on his fourth bulldozer and still doing his job—clearing the way for the infantry.