ARLINGTON, Va. The rows of simple white headstones in the broad expanses of brilliant green lawns are scrupulously arranged, and they seem to go on and on, endlessly, in every direction. It was impossible not to be moved. A soft September wind was the only sound. Beyond that was just the silence of history, and the collective memory of the lives lost in its service. Nearly 300,000 people are buried at Arlington National Cemetery, which is just across the Potomac from Washington. On Tuesday morning I visited the grave of Air Force Second Lt. Richard VandeGeer. The headstone tells us,...