Flags representing fallen soldiers on the Mall for Memorial Day in Washington, D.C., on May 29. (Andrew Caballero-Reynolds/AFP/Getty Images)

THE COUNTRY’S war dead are a kind of closed society, elevated above us by service and sacrifice — in Shakespeare’s words, “a royal fellowship of death.”

We can talk of their courage and sacrifice and make speeches praising their patriotism, but we really have only an inkling of how men (and an increasing number of women) have faced the horrors of combat — and what motivated or compelled them to fight and risk their lives. What we do know is that we have an obligation to honor selflessness and devotion to duty and to ensure that the memory of the dead will not expire with those who bore their loss.

In July, in the early stages of his improbable progress toward the Republican presidential nomination, Donald Trump was asked about his differences with Sen. John McCain (R-Ariz.), whom he had described as a “loser.” The questioner asked if it was appropriate to use such language about “a war hero,” and Mr. Trump replied, “He’s a war hero because he was captured. I like people that weren’t captured.” The answer was childish and flippant, and wholly characteristic of the steady stream of puerile insults, half-truths, untruths and innuendo that make up much of Mr. Trump’s campaign. Like most of us, Mr. Trump has no experience of what people confront in war, though he has made it widely known that he went to a really tough military school for teenage boys.

There are, however, many thousands of witnesses who have at least some understanding of what war is like and what it demands. Many suffered wounds of mind and body that will never heal. Mr. McCain, who was tortured and tormented by the North Vietnamese over a period of 5½ years, steadfastly refused to be released ahead of those captured before him.

Was he a hero? In fact, he and the others imprisoned in North Vietnam didn’t consider that kind of stubbornness to be an act of heroism. It was, rather, part of an unbreakable code they lived by, based on duty, honor, unselfishness and a sense of obligation to one’s fellows. It was a similar, unwritten set of standards — steadiness, reliability, courage and a dogged determination not to let the other guy down — that many Americans maintained to the end of their tragically shortened lives in wars dating back two centuries and more.

We haven’t heard much about such qualities in this campaign. Memorial Day would be a good time for candidates of every persuasion who are seeking high office in this country, and for the rest of us too, to start giving some thought and attention not to what we are owed that will enhance our own comfort and security but to what we owe those who went before — that fellowship of death. We could honor them at least in some small measure by standing for what is right and honest rather than what is politic.