It has been 65 years since D-Day—the early June day when the United States and its allies launched a massive attack on the shores of Normandy in a bid to liberate western Europe from the Nazis. It's been long enough for most people who still remember the date to have come to think of its success as natural and foreordained. But of course it was neither of these things. Supreme Allied Commander of the Allied Expeditionary Force Dwight D. "Ike" Eisenhower himself gave it no better than a 50-50 chance of success, even if the weather was good and everything went right.

As it turned out, the weather was so bad that he had to postpone the invasion by 24 hours once the troops were already aboard the ships and boats. Battalion after battalion was forced to land miles from where they were supposed to be, facing terrain totally unlike what they had trained for. High seas and nervous coxswains under fire for the first time "landed" many troops into water that came over their heads. Men laden with more than 100 pounds of equipment and ammunition sometimes sank to the bottom and drowned, their bodies eventually washing ashore to join those who had been killed the moment their feet touched the beach.

When we think of the forces under Ike's command on the night of June 4, as he faced the question of whether to postpone the invasion once more, they seem—in these days when placing 40,000 combat troops somewhere is a huge political and military decision—overwhelming: he had over a million men, 5000 vessels of all sizes, including battleships, and 10,000 aircraft. On the morning of June 6, if he decided to go on that date, he would land 73,000 Americans, 66,000 Britons, and 20,000 Canadians on the shores of Normandy. These were big numbers, but facing them was a German army still better trained, more experienced, better armed, and motivated by a high degree of fanatical zeal; an overwhelmingly strong armored force that could reach the invasion beaches in 24 to 48 hours; formidably well-planned fortifications; and, in the person of Field Marshal Erwin Rommel, one of the war's most daring and brilliant battlefield commanders. Victory was no sure thing.

On the morning of June 6, it was still just possible for Hitler to win the war, however slim the margin. Failure on D-Day and the withdrawal of the surviving troops might have encouraged Stalin and Hitler to embrace, might have cost FDR the election in November, and might have led to making the defeat of Japan America's first priority. Certainly D-Day could not have been easily or quickly repeated. British manpower was strained to the utmost, and a whole new army could hardly have been formed. Ike could not know that Hitler had kept the four strongest German armored divisions under his control, to be released only on his explicit command. Nor could Eisenhower know that he had succeeded in fooling the Germans into believing that the