Donald Trump embraced anti-Bush conspiracy theories. Ted Cruz yelled at Marco Rubio in Spanish. And somehow, the whole GOP field seemed to elevate their game in what was the craziest contest of a seemingly endless debate season.

For much of the night there seemed like there were two major fault lines. The first and most visible was between Trump and Jeb Bush, the billionaire’s favorite foil. The second was between the two men fighting to become the first Hispanic president of the United States and, more importantly in terms of the Republican nomination, about which one should become the conservative alternative to Trump.

This is, after all, still Trump’s race to lose. Coming off a landslide victory in New Hampshire, the oft-profane lapsed Christian is leading his opponents in the South Carolina polls by double digits. Yet he trained most of his fire on Jeb, the patrician former Florida governor who may have successfully reframed his fourth-place finish in New Hampshire into some kind of victory.

It’s not surprising, really. Trump loves mocking Jeb. Unfortunately for The Donald, however, Jeb may have finally learned how to fight back.

The fireworks really started with a question about Jeb’s brother, George W. Bush, who is set to join his brother on the campaign trail on Monday. Moderator John Dickerson asked Trump point blank if he stood by his 2008 comments that Bush deserved to be impeached for allegedly misleading the public about the reasons for going into Iraq, a reminder that Trump has spent much of his life as a left-leaning critic of the GOP.

Trump didn’t restate his call for impeachment. But he didn’t disavow it, either. “You do whatever you want,” he said, seeming to provide Dickerson with the option of impeaching Bush himself. “You call it whatever you want."

Then Trump went on to say something even more unusual in a Republican primary. He suggested that the former GOP president, George W. Bush, directly lied to the American public in order to overthrow Saddam Hussein.

“I will tell you. They lied. And they said there were weapons of mass destruction and there were none. And they knew there were none. There were no weapons of mass destruction,” Trump said.

Trump’s assertion was bizarre for a Republican—or, for that matter, anyone running for president. While the conventional wisdom may hold that the 2003 invasion of Iraq was mistaken, or even disastrous, it’s rare to hear any politician insist that George W. Bush willingly misled the American people into war. “Bush lied, people died,” is a sentiment rejected by even the most ardent opponents of the Iraq War, a fringe belief usually embraced by cranks on the far-right and far-left. On Saturday, Donald Trump brought that conspiracy theory to a presidential debate.

But a newly energized Jeb Bush—and the crowd at the debate—wasn’t having it.

“I’m sick and tired of Barack Obama blaming my brother for all of the problems that he’s had,” Bush said to roaring feedback. “And, frankly, I could care less about the insults that Donald Trump gives to me. It’s blood sport for him. He enjoys it. And I’m glad he’s happy about it.”

Bush has been one of the few candidates to respond to direct attacks from Trump in debate after debate.

And it seemed that in friendly territory—the Republican establishment in South Carolina has long been partial to the Bush dynasty—everything finally clicked for him.

“My dad is the greatest man alive in my mind. And while Donald Trump was building a reality TV show, my brother was building a security apparatus to keep us safe,” Jeb said. “And I’m proud of what he did.”

As Trump stumbled looking to find a way to bully Bush, he reached for the final card in his deck. “The World Trade Center came down during your brother’s reign,” Trump said to loud boos from the crowd. “Remember that.”

But where this line worked for him in the past against Cruz, in the infamous “New York values” fight, it gave Bush no pause here.

“He’s had the gall to go after my mother...I won the lottery 63 years ago when I looked up and saw my mom. My mom is the strongest woman I know. This is not about my family or his family,” Bush replied, cooly—the first time in a long while he wasn’t wincing at Trump’s barbs. “This is about South Carolina families that need someone that can be the commander in chief that can lead. I am that person.”

Jeb might have gotten the better of Trump in that exchange, but their rivalry wasn’t the root of every fight at Saturday’s memorable debate. The biggest story of the evening, of course, was the death of Supreme Court Justice Antonin Scalia, the conservative movement’s foremost legal mind. And as the most distinguished attorney in the GOP race, Cruz saw his moment to portray himself as the most qualified man to pick his replacement.

Unfortunately for Cruz, Rubio also saw tonight as the perfect moment to attack his enemy’s strengths.

As The Daily Beast’s Betsy Woodruff and Tim Mak report, Cruz spoke glowingly in private email discussions about now-Chief Justice John Roberts, a man now despised by much of the conservative base for ruling in favor of Obamacare’s constitutionality. Those emails matched Cruz’s public praise for Roberts—including a National Review op-ed calling him “brilliant.”

Cruz has since tried to walk some of that praise of Roberts back. And in the debate tonight, Trump hit him over the inconsistency—and hit him hard. The mogul initially directed his criticism at Jeb Bush, dinging him for his brother’s appointment of Roberts. But he mentioned Cruz in that breath, so Cruz jumped in.

“I did not nominate John Roberts,” he said. “I would not have nominated John Roberts.”

“You pushed him, you pushed him!” Trump retorted.

“Donald, Donald—” Cruz replied.

“Why do you lie?” Trump shot back.

“Donald, adults learn not to interrupt each other,” he said.

“Yeah, yeah, I know, you’re an adult,” Trump said, voice dripping with contempt. “You’re an adult.”

“I did not nominate him,” Cruz insisted again.

Of course, it’s completely correct that Cruz didn’t nominate Roberts; Cruz was not president of the United States in 2005. But, as Cruz’s own email and op-ed make abundantly clear, he was a vocal and adoring booster of Roberts during his confirmation hearing process.

And that wasn’t the only heated exchange the two had Saturday. During a fight over immigration, Rubio, who co-sponsored an immigration reform overhaul with Democrats early in his Senate career, used a very narrow definition of “amnesty” to insist he’d never supported a no-consequence path to citizenship for undocumented aliens. Cruz insisted that Rubio’s plan was, in fact, amnesty—and that plan had been defeated thanks to Cruz’s efforts.

Rubio shot back that Cruz wanted immigration reform as well—that he wanted more immigration into the country. Cruz replied that Rubio had “a long record in favor of amnesty,” and that he promised on the Spanish-language Univision channel television to uphold President Obama’s pro-immigration edicts. Rubio then said that there’s no way Cruz could know that because the Texas senator doesn’t speak Spanish, which provoked Cruz to begin yelling at Rubio in Spanish.

“For a number of weeks Ted Cruz has just been telling lies,” Rubio said as Cruz attacked him in Spanish. “He lied about Ben Carson in Iowa. He lies about Planned Parenthood and marriage. And he makes things up. The bottom line is this is a campaign and people are watching. Here is the truth—Ted Cruz supported legalizing people in this country.”

As with all these Republican debates, it’s tough to say who had the best night. Trump remains the frontrunner, the man supposedly too uncouth to win over South Carolina’s polite, Southern voters. Yet he still leads a crowd of career politicians still struggling to figure out a strategy to beat him as the race turns to the South, where a deeply religious electorate has showed every sign of embracing New York City’s premier outer-borough vulgarian.

But all of Trump’s main rivals showed up Saturday night. They were concise, articulate, and at times (to use a Trumpism), classy. So if The Donald somehow starts to slip—if his lead in South Carolina narrows, if a clear alternative to his slow march to the nomination develops—this debate will likely be seen as the turning point, the moment when the man who’s thrown out every rulebook in politics finally learns that a few rules still apply. Like not trashing a Republican president in a deep red state’s GOP primary, for starters.

Or, more likely, no clear alternative rises from tonight’s pileup, as Trump continues his divide-and-conquer undoing of the modern Republican Party. The rest of the field will continue to take votes from each other as Trump secures his winning plurality and puts together his second big win.

Either way, it made for fantastic television, perhaps the most entertaining debate in a race that’s been full of them. And win or lose, that’s an outcome that a TV guy like The Donald, who is known to occasionally refer to polls as “ratings,” will likely appreciate.

— with additional reporting by Gideon Resnick