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.