Some dates live on in the American folk memory long after the events themselves are distant history—October 12, 1492; July 4, 1776; December 7, 1941. Few if any of us, however, know the significance of July 1, 1916. But that date, a century gone, is seared into the soul of the British nation. It was the first day of the Battle of the Somme, when 120,000 men of the British army went “over the top” and attacked the German trenches. By day’s end, 19,240 of them were dead, 35,494 were wounded, 2,152 were missing, and 585 were prisoners of war. That’s a total of 57,471 casualties—a staggering 47 percent of the men who left the trenches that day.