So, it happened. President Barack Obama met with President-elect Donald Trump at the Oval office -- for an hour and a half --Tuesday and both spoke cordially about each other to the press afterwards. Yes, really.

SEE ALSO: Donald Trump descends on White House for most uncomfortable icebreaker ever

"I very much look forward to dealing with the president in the future," Trump said, smiling at the press scrum and adding that Obama told him about "some of the really great things that have been achieved."

"Mr President, it was a great honor being with you, and I look forward to being with you many more times in the future." Again, yes really.

The language was unexpected, and a strange kind of welcome relief after an interminable election race that has been mired in insults and mud-slinging. It was also the pivot to end all pivots following Trump's long history of attacking Obama.

Here's a look at some of his previous thoughts on the president. It's interesting to note his change of tone upon entering the White House.

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When he failed to correct someone who called Obama a Muslim

"We know our current president is a Muslim," one supporter declared during a Q&A in New Hampshire in September 2015. Trump avoided the opportunity to put him right and allowed the guy's allegation to float unchallenged.

When he questioned Obama's birthplace

Trump has been questioning whether Obama was born in the U.S. for years. As far back as 2011 he was asked why he doesn't give the issue up, but maintained he had his "doubts." He finally changed his tune and told us all Obama was born in the U.S. in September.

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When he said Obama founded ISIS

In Florida in August, Trump suggested Obama launched the terrorist organization. Asked to clarify -- or who knows, even retract -- his outlandish statement on radio the next day Trump said, "No, I meant he's the founder of ISIS."

When he questioned Obama's position as president

Trump referred to Obama as the "quote 'President'" at a rally as recently as October, shortly after the tape of his obscene comments was leaked.

When he tweeted that Obama will go down as the worst president of the United States

Obama read that tweet out on Jimmy Kimmel Live, and replied, "at least I will go down as a president." Ah.

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When they met each other

It sounds like Obama was happy to overlook Trump's past form for their meeting on Thursday, and of course Trump put aside Obama's attacks and gags, which might help this whole peaceful transfer of power thing.