WASHINGTON (AP) — When Jim Mattis announced his resignation as defense secretary, President Donald Trump thanked him for "tremendous progress" in helping to rebuild the military and for "retiring with distinction." Times changed and so did Trump's story about losing his Pentagon chief.

Trump now claims he fired Mattis, says President Barack Obama did the same and takes credit for nicknaming him Mad Dog Mattis. None of that is true.

After leaving the administration, Mattis let it be known that he was biting his lip about Trump's leadership. He only hinted at his concerns — even in a recent book — until his statement this week opening up on "the first president in my lifetime who does not try to unite the American people — does not even pretend to try."

Trump lashed back.

TRUMP: "Probably the only thing Barack Obama & I have in common is that we both had the honor of firing Jim Mattis, the world's most overrated General." — tweet Wednesday.

THE FACTS: That's not what happened in either case. Mattis resigned as defense secretary in protest over Trump's decision to pull U.S. troops from Syria, giving two months' notice.

The retired four-star Marine general announced on Dec. 20, 2018, that he would step down in February 2019. "General Jim Mattis will be retiring, with distinction," Trump tweeted then, praising him as a "great help" in getting allies to put up more money for their military obligations. "I greatly thank Jim for his service!"

But the matter didn't sit well with Trump and three days later he abruptly said he was bringing in a replacement Jan. 1, 2019, not waiting until the next month.

Former White House chief of staff John Kelly told The Washington Post in an interview Thursday, "The president has clearly forgotten how it actually happened or is confused."

Obama also didn't fire Mattis, who served as head of the military's Central Command in his administration. Mattis departed a few months earlier than expected in 2013, in part because of disagreements over Iran.

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TRUMP: "His nickname was 'Chaos', which I didn't like, & changed to 'Mad Dog.'" — tweet Wednesday.

THE FACTS: No, he didn't change Mattis' nickname to Mad Dog, as he often claims to have done. Mattis had been called that for more than a decade before joining the Trump administration.

The Marine general had that moniker dating at least to 2004, when he was commanding general of the 1st Marine Division. He attributed the nickname to the press, though old press accounts said that's what his troops called him in Iraq.

He was also known by his military call sign Chaos when he was a Marine colonel. Mattis joked that it stood for "Colonel Has An Outstanding Solution."

When Trump took to calling Mattis "the world´s most overrated general" after their rupture, Mattis gave himself a new nickname: "the Meryl Streep of generals."

"I'm honored to be considered that by Donald Trump because he also called Meryl Streep an overrated actress," he cracked at a New York charity dinner in October.

In his rebuke Wednesday, Mattis assailed Trump's use of military force to quell protests near the White House and said his former boss was setting up a "false conflict" between the military and civilian society. "I have watched this week's unfolding events, angry and appalled," Mattis wrote.

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EDITOR'S NOTE — A look at the veracity of claims by political figures.

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