I’VE BEEN THINKING A LOT RECENTLY ABOUT the astonishing responsibility that lay on the very young shoulders of junior tank commanders during the war. Take John Semken, for example, of the Sherwood Rangers Yeomanry, a British armored regiment. On October 25, 1942, Semken, then a lieutenant and just 21, was pausing in his Sherman tank on the second morning of the Battle of El Alamein. It had been
