John Arquilla is professor of defense analysis at the U.S. Naval Postgraduate School and author of Worst Enemy: The Reluctant Transformation of the American Military.

All of our nation's veterans are honored on November 11, but it is important to recall that the origin of this observance was revulsion at the horrific casualties suffered by so many countries during World War I. Yes, a second and even more destructive conflict followed all too soon after the "war to end all wars," impelling a name change from Armistice Day to Veterans Day. And the rest of the 20th century was littered with insurgencies, terrorism, and a host of other violent ills -- most of which persist today, guaranteeing the steady production of new veterans, of which there are 22 million in the United States.

But despite the seemingly endless parade of wars waged and fresh conflicts looming just beyond the bloody horizon, World War I still stands out for its sheer horror. Over ten million soldiers died, and more than twice that number were wounded. This is a terrible enough toll. But what makes these casualties stand out even more is their proportion of the total numbers of troops mobilized. For example, France put about 7.5 million soldiers in the field; one in five died, and three out of four who lived were wounded.

The other major combatants on both sides suffered horribly as well: the Austro-Hungarian Empire's 6.5 million soldiers had a combined rate of killed and wounded of 74 percent. For Britain and Russia, the comparable figures totaled a bit over 50 percent, with German and Turkish losses slightly below one-half of all who served. The United States entered the conflict late, and so the overall casualty rate for the 4.3 million mobilized was but 8 percent. Even so, it is more than double the percentage of killed and wounded from the Iraq War, where total American casualties amounted to less than 4 percent of the one million who served.

Few conflicts in all of military history have seen victors and vanquished alike suffer such shocking losses as were incurred in World War I, so it is worth taking time to remember how this hecatomb came to pass...