Seventy-five years ago, at the Battle of the Bulge (fought from Dec. 16, 1944, to Jan. 25, 1945), the United States suffered more casualties than in any other battle in its history. Some 19,000 Americans were killed, 47,500 wounded and 23,000 reported missing. The American and British armies were completely surprised by a last-gasp German offensive, given that Allied forces were near the Rhine River and ready to cross into Germany to finish off a crippled Third Reich. The Americans had been exhausted by a rapid 300-mile summer advance to free much of France and Belgium. In their complacence, they...