(ABC NEWS) -- The second presidential debate came at the end of a tumultuous and unprecedented week on the campaign trail, and the battle between Hillary Clinton and Donald Trump reflected every bit of that drama.
The Republican and Democratic presidential nominees faced off in the town hall-style debate, which was co-moderated by ABC News’ Martha Raddatz and CNN’s Anderson Cooper at Washington University in St. Louis.
The fireworks started early and carried through the debate’s 90 minutes. Here are eleven moments that mattered at Sunday night’s debate:
1. No Great Shakes
Breaking with what is a political debate tradition, Trump and Clinton didn’t shake hands at the start of the night.
Instead of sticking with formality and shaking Trump's hand, Clinton merely nodded in his direction, saying, "Hello."
The snub -- on the part of both candidates -- was a window into the tension that permeated the night.
2. Trump and Clinton React to His Vulgar 2005 Recording
Trump said he’s “very embarrassed” by his vulgar comments that were recorded in 2005 when he talked about his ability to make advances on women because of his fame.
“I hate it but it’s locker room talk,” he said tonight.
“This was locker room talk. I’m not proud of it. I apologized to my family. I apologized to the American people. Certainly I'm not proud of it. But this is locker room talk,” he said.
When pressed by co-moderator Anderson Cooper whether he ever did any of the actions he described in the tape, which included kissing women against their will and groping their genitalia, Trump said he had not.
Clinton said it's clear to anyone who heard the video that it represents "exactly who he is."
"We have seen him insult women. We’ve seen him berate women; on their appearance, ranking them from one to 10. We saw him after the first debate spend nearly a week denigrating a former Miss Universe in the harshest, most personal terms," Clinton said.
"So, yes, this is who Donald Trump is."
3. Trump Brings Former Clinton Accusers Into Debate
Trump used old sex assault claims against Bill Clinton as a way to attack Hillary Clinton during tonight’s debate.
While answering a question about the recordings of his talking about women in a vulgar fashion, Trump deflected to say that he was not the worst offender.
“If you look at Bill Clinton, far worse, mine are words, and his was action. His was — what he’s done to women, there's never been anybody in the history of politics in this nation that's been so abusive to women....Hillary Clinton attacked those same women. And attacked them viciously, four of them here tonight,” Trump said.
The women in question are Paula Jones, Juanita Broaddrick, and Kathleen Willey, all of whom have accused former president Bill Clinton of either having a sexual relationship with them or making unwanted sexual advances; the fourth is Kathy Shelton, who was raped at the age of 12 and whose alleged attacker was represented by Hillary Clinton.
Trump appeared at a news conference hours before the debate with the four women, all of whom are supporting him in this election.
4. Candidates Issue Dueling Demands for Apologies
Both candidates demanded apologies from each other for the false “birther” theory that President Obama was born in Kenya, and not Hawaii, which Trump pedaled for years after first bringing it up during the 2012 election.
Clinton attacked Trump, arguing that the Republican nominee “never apologizes for anything to anyone.”
“He owes the president an apology, he owes our country an apology and he needs to take responsibility for his actions and his words,” Clinton said.
But accusing Clinton’s 2008 campaign of starting the “birther” conspiracy about Obama, Trump said, “Well, you owe the president an apology because, as you know very well, your campaign's Sidney Blumenthal; he’s another real winner that you have and he’s the one that got this started, along with your campaign manager.”
“So you really owe him an apology.” Trump said.
No evidence has been uncovered to link the idea of birtherism to the Clinton campaign.
Trump also hit Clinton for the private email server she used as secretary of state. “I think the one and the thing you should be apologizing for and the thing that you should be apologizing for are the 33,000 e-mails that you deleted,” he said.
5. Trump’s ‘Exploding’ Campaign
When asked about the private email server she maintained when she served as secretary of state, Clinton admitted once again that she made a mistake. And, after Trump’s response, Clinton said she’d like to move on to the questions from the audience.
Trump interjected, “And get off this question.”
“Ok, Donald, I know you're into big diversion tonight,” Clinton said.
“Anything to avoid talking about your campaign and the way it's exploding and Republicans are leaving you,” Clinton said, referring to the number of GOP congressional members who, over the weekend, said they wouldn’t vote for Trump because of the 2005 tape in which Trump is heard making lewd comments about women.
6. Trump Says Muslim Ban ‘Morphed’
One of the town hall participants, a Muslim, asked,“ With Islamophobia on the rise, how will you help people?” Trump didn’t answer, instead saying, "We have to be sure that Muslims come in and report when they see something going on, when they see hatred going on.”
Clinton went next, saying, "My vision is an America where everyone has a place if you are willing to work hard and do your part and you contribute to the community. That's what America is. That's what we want America for our children and grandchildren. It's short-sighted and dangerous to be engaging in the kind of demagogic rhetoric that Donald has. We want Muslims to be on the side of our eyes and ears.”
In a follow-up, Raddatz asked Trump about his temporary Muslim ban and whether it was "a mistake to have a religion test.” Trump then acknowledged his ban has “morphed.”
"The Muslim ban is something that in some form has morphed into an extreme vetting from certain areas of the world,” Trump said. When Raddatz asked about how the policy morphed, Trump again said, "It is called extreme vetting.”
7. Trump Threatens a Special Prosecutor for Clinton Emails
Trump said that if elected, he plans to appoint a special prosecutor to investigate Clinton’s emails.
“I’ll tell you what, I didn’t think I’d say this, but I’m going to say it, and I hate to say it, but if I win, I am going to instruct my attorney general to get a special prosecutor to look into your situation, because there has never been so many lies, so much deception, there has never been anything like it, and we're going to have a special prosecutor,” he said.
This is not the first time Trump has called for a criminal investigation into Clinton’s emails. On the campaign trail, Trump has expressed frustration over the Justice Department’s decision not to recommended charges against Clinton and has accused the FBI of politicizing the investigation.
“In my opinion, the people that are the long-term workers at the FBI are furious,” Trump said. “There has never been anything like this, where emails, and you get a subpoena, you get a subpoena and after getting the subpoena you delete 33,000 e-mails.”
Trump said Clinton took special measures to delete email correspondence from her time at the State Department. “You acid wash, or bleach them, as you would say, a very expensive process,” Trump said.
When asked to respond by Raddatz, Clinton brushed off Trump’s claims.
“Everything he just said is absolutely false,” she said. “But I’m not surprised.”
Clinton then concluded, "It's just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country."
Trump quickly hit back, "Because you'd be in jail."
8. Trump Says, ‘Of Course,’ He Used Loopholes to Avoid Paying Federal Income Taxes
Trump said that, “of course,” he used the tax provision that allowed him to use a business loss to avoid paying federal income taxes for years.
Trump’s tax returns and payments have been a controversial part of the presidential campaign because he has not released the documents, as is common practice for presidential candidates, saying that he under audit.
A portion of his 1995 tax returns were leaked to The New York Times and those pages showed that he claimed a $916 million loss, which could have allowed him not to pay personal federal income taxes for a number of years afterward.
When asked whether he used the loss “to avoid paying taxes,” Trump said, “of course I do, and so do all of her donors.”
“I understand the tax code better than anyone and it's complex,” Trump said.
“I pay tremendous numbers of taxes and I used it and so did Warren Buffett and George Soros and the other people,” Trump said, naming two well-known Clinton supporters.
When asked whether he can say how many years he did not pay taxes, Trump said he could not.
9. Trump Breaks With Running Mate Mike Pence
Raddatz asked Trump what he would do about Syria and the humanitarian crisis in Aleppo if he were president, and reminded Trump of running mate Pence’s position.
Pence had taken the position during the vice presidential debate that the United States should be prepared to strike the military targets of the Assad regime, referring to Syrian President Bashar al Assad.
But contradicting his running mate, Trump said tonight, “He and I haven't spoken and I disagree.”
“I think we have to knock out ISIS. Right now, Syria is fighting ISIS,” Trump added.
In a change of tone, town hall participant Karl Becker posed a final question to Trump and Clinton. “Regardless of the current rhetoric, would either of you name one positive thing that you respect in one another?”
“I think that's a very fair and important question,” said Clinton. “I respect his children. His children are incredibly able and devoted and I think that says a lot about Donald. I don't agree with nearly anything else he says or does, but I respect that and think that is something that as a mother and a grandmother is very important to me. So I believe that this election has become in part so conflict-oriented and so intense because there is a lot at stake.”
Trump accepted Clinton’s compliment, in turn taking the opportunity to compliment her as well. “She doesn't quit and doesn't give up. I respect that. ... She is a fighter. I disagree with much of what she is fighting for. I do disagree with her judgment in many cases, but she fights hard and doesn't quit or give up, but that is a good trait.”
11. Trump Looms Behind Clinton
In the town hall format, the candidates were allowed to roam around the stage, remaining standing or sitting while their opponent answered a question.
At one point, Trump stood curiously close to Clinton, listening to her respond to a question from an audience member on the Affordable Care Act -- a moment that many noted on social media.
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