One last thing. Cindy Sheehan’s son, Casey, and Humayan Khan died just 65 days apart in Iraq in 2004. The next year, when Sheehan became an idol of the antiwar cause in an increasingly bitter debate over Iraq, Democrats expressed great admiration for her.

Now, with Democrats having nominated a candidate who voted to authorize the Iraq war (only later to oppose it), against a Republican who regularly calls the war a disaster and says he opposed it from the beginning, another Gold Star parent, Khizr Khan, has become a cause — but in an entirely different context.

It seems unlikely that the Clinton campaign would have given the anguished parents of a son or daughter who died serving in Iraq the opportunity to tell the convention that the war should never have been authorized or fought. But when the Clinton campaign ran across Humayun Khan’s story and realized how useful the Khans might be against Trump on the issues of Islam and immigration, the grieving parents were quickly invited to Philadelphia.

The Khans represent a small group. Humayun Khan was one of just 14 Muslim-Americans (the number was compiled by the House Homeland Security Committee) among the 6,885 U.S. troops who have died in Iraq and Afghanistan. But his parents’ anguish is very real and their story very powerful. And it will undoubtedly be used against Trump many times between now and November.