No one gets the fascination with Michelle Obama, fashion plate, more than her husband. Invoking another president with a glamorous wife—that would be, maybe, John F. Kennedy? — President Obama told military guests at the Commander in Chief Ball last night, “I have the special honor of being the guy who accompanied Michelle Obama to the ball.” That got a big laugh, but it would be a few minutes before the first lady made her entrance, in an ivory chiffon dress. But when she did, oh, what a roar. It was an amazing day for Mrs. Obama — chic and...