Memorial Day originated to honor those who lost their lives in the Civil War. But many of us view it as simply an opportunity to kick off summer with backyard barbecues or three days in the mountains.

Such casual celebrants are as unlikely to dwell on the agonies of Antietam as they are to remember the epic struggle waged by trade unions to win the 40-hour work week over Labor Day.

Such historical amnesia is unfortunate. The life we Americans live today would not even have been possible without the courage and sacrifice of those veterans who, from Concord Bridge to Herat and Baghdad, have given “the last full measure of devotion” to win and protect U.S. independence. Their valor and skill have preserved the “government of the people, by the people, for the people” that, however imperfectly, today melds the dreams of 300 million Americans into a society of ordered liberty in which those dreams, forged by hard work, can grow to fruition.

Honoring our veterans, living and dead, should not be confused with simple blind patriotism. Dissent is not only an honorable American tradition, it is protected by the very Constitution our fighting men and women fought to preserve. The bitter dissent during the Vietnam War and the growing disquiet over the U.S. role in Iraq thus have long and honorable antecedents.

Yet, there is a kind of social contract honored by both American veterans and critics of U.S. policies. Soldiers seldom get to pick their wars, responding loyally when called to the colors by the elected civilian leadership and never once in this nation’s long history misusing the power they command to impose military rule.

That’s why every American should have paused on May 29 to honor America’s veterans.