President Trump’s sensitivity to criticism has long played to his political benefit. Criticize him, and as a number of Republican members of Congress have found out, you are at risk of losing your support and your job.

That’s a version of what just happened to the British ambassador to the United States, Sir Kim Darroch, who resigned Wednesday after cables leaked that showed him calling Trump “inept” and “insecure.”

The British ambassador was literally doing his job by informing his colleagues on the state of U.S. politics, and diplomats have pointed out that this kind of talk happens on both sides. Trump took such great offense that the diplomat of another country had to step down to appease him.

How Trump did this is a case study in how he commands loyalty by refusing to let any slight go. Here’s how this British ambassador-Trump spat went down, in their own words:

Darroch, in secret memos to British politicians about Trump, which leaked Sunday in the British tabloid the Daily Mail.: “We don’t really believe this Administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept.”

"I don't think this Administration will ever look competent."

"For a man who has risen to the highest office on the planet, President Trump radiates insecurity."

"This is a uniquely dysfunctional environment."

There was also some positive stuff, relatively speaking, buried in there, like: Trump may “emerge from the flames, battered but intact, like [Arnold] Schwarzenegger in the final scenes of The Terminator.”

"Do not write him off."

Trump, on Sunday, made clear he wanted the author of these memos gone: “We’re not big fans of that man, and he has not served the U.K. well.”

Outgoing British Prime Minister Theresa May tried to make amends without backing down: She said Darroch has her “full support” and that the cables “do not reflect the closeness of, and the esteem in which we hold, the relationship."

That wasn’t good enough for Trump. On Monday, he delivered the line that was probably the death knell for Darroch: “We will no longer deal with him.”

The British Embassy declined to comment.

Trump, on Tuesday, kept up the insults: “The wacky Ambassador that the U.K. foisted upon the United States is not someone we are thrilled with, a very stupid guy.”

"I don’t know the Ambassador but have been told he is a pompous fool."

On Wednesday, a once-defiant British diplomatic corps recognized that they had lost. “[T]he current situation is making it impossible for me to carry out my role as I would like,” Darroch wrote in a letter to his colleagues.

May also thought it was a shame, saying Darroch’s departure was a “matter of great regret that he has felt it necessary to leave his position."

"Good government depends on public servants being able to give full and frank advice,” she said. “I hope the House will reflect on the importance of defending our values and principles, particularly when they are under pressure.”

But it was she and the British ambassador who gave way to relentless pressure from Trump.