Commentary If there ever was a day in the American calendar that invites reflection, it’s Memorial Day. Over the course of our country’s history, hundreds of thousands of Americans—most of them young and with decades of life still ahead of them—made the ultimate sacrifice. Some were killed by enemy fire; others by what is called, with the grimmest irony, “friendly fire.” Some lost their lives in training accidents. Others perished from diseases, most notably the masses of doughboys wiped out by typhus in the trenches of World War I. Every military fatality is heartbreaking and worth remembering on Memorial Day, regardless of the cause of death. Noncombat deaths, such as the training accidents that tragically occur from time to time, demonstrate that preparing for war can be as lethal as war itself. Those who perish in such accidents deserve every bit as much honor as those who die in battle, …