Mark it down.

The weekend of July 18-19 is when Donald Trump’s presidential candidacy came to a screeching halt.

That’s the good news.

The bad news — which in reality is good news — is that (a) he doesn’t realize it, (b) he’ll refuse to realize it and (c) he’ll stay the course for as long as he can.

Trump decided to self-immolate his campaign by declaring to a conservative audience that he preferred U.S. military veterans “who weren’t captured.” That was his inimitable way of denigrating the heroic service of another Republican presidential candidate, 2008 GOP nominee John McCain.

Sen. McCain, of course, was captured by North Vietnam when his plane was shot down in 1967. He suffered grievous injuries, which weren’t treated properly his captors.

He spent more than five years in captivity. He came out in 1973, along with hundreds of other POWs, after the United States agreed to a negotiated end to the Vietnam War.

Trump, though, didn’t serve in the military. He got those deferments, allowing the war to swallow up millions of other young Americans.

He didn’t have a chance in hell of being nominated by the Republican Party, let alone getting elected as the 45th president of the United States.

This latest bit of verbal excess just seals the deal.

If his chance of nominated was next to nil before, it’s now really at — or below — that level today.

But, heck, don’t drop out, Donald. Some of your GOP foes think you’ve disgraced yourself enough. Get out, man, they’re imploring him.

Stay in, Donald. Another fellow GOP candidate, Sen. Ted Cruz of Texas, thinks The Donald deserves to be heard. I do, too.

However, he’s going to find it harder and harder to get his message heard above the laughter — and the boos.