The two old sailors stepped side by side toward the Tomb of the Unknowns, carrying a memorial wreath to their shipmates between them. The crowd stood hushed in the autumn sun while the pair, in ball caps and blazers, approached the white marble monument, left their wreath, stepped back and saluted. A bugler had just played taps, and as the breeze rustled a majestic elm nearby, the moment was almost perfect: Few seemed focused on the jagged crack that zigzagged through the 48-ton stone like a scar, or the dings and chips in its surface. But away from the scene...