CLEVELAND, Ohio - Republicans tried to forget their differences with their maverick presidential candidate Donald Trump as they opened their national convention Monday with a pledge to strengthen Americans’ security at home and abroad.

For his part, Trump made a theatrical entrance, as Queen’s “We are the Champions” played in darkened arena and Trump walked through ersatz fog to the podium.

“We’re going to win so big,” he said three times.

He then introduced his wife, Melania, who said Trump will work for all Americans.

“If you want someone to fight for you and your country,” she said. “I assure you, he’s the man. He will never, ever give up. And most importantly, he will never let you down.”

Donald Trump’s brief appearance, and the calls for unity throughout the convention’s first day, came after a floor fight broke out among delegates on the convention floor over an attempt to free delegates to vote for a candidate other than Trump.

Supporters of other potential candidates booed the first voice vote to adopt rules that would bind delegates to Trump to assure his nomination.

After brief speeches by GOP leaders supporting the rules and the party platform and a brief walkout by the Colorado delegation, the rules were adopted in a second voice vote.

“We will be the people to make America great again,” said Rep. Virginia Foxx of North Carolina, who called American values a “divine calling.”

“And if anyone is wondering when, the answer is now!” she said.

“They quashed the voice of the people,” said Kendal Unruh, a Colorado delegate who had wanted to free delegates to vote for other candidates and who supported Sen. Ted Cruz (R-Texas).

Unification is the major goal of the party and Trump this week in Cleveland. Republicans are trying to focus on defeating presumptive Democratic presidential nominee Hillary Clinton and protecting the United States and its troops overseas from terrorism.

But Trump faces significant challenges. He has alienated many in the party establishment with personal attacks on party figures who have declined to endorse him or are at odds with him over his comments about minorities and immigration.

Ohio Gov. John Kasich was among many top Republican office holder who stayed away from the convention, maintaining as he did in the presidential primaries that Trump lacks the temperament to be president.

Among the key themes among speakers Monday was the terror attack on the U.S. Embassy in Benghazi that left four Americans dead in 2012. Politicians and military figures accused Clinton of failing to protect Americans in her charge.

Patricia Smith, whose son, Sean, died in the Benghazi attack, made an emotional plea and a personal attack on Clinton who she said allowed the embassy to be underprotected then lied about the terror attack, out of concern about offending Muslims.

“I blame Hillary Clinton personally for the death of my son,” Smith said. “How could she do this to me? Donald Trump is everything Hillary Clinton is not. He is blunt, correct and strong.”

Ex-Marine Mitchell Zuckoff, who wrote the book, “13 Hours,” about the Benghazi attack, said Clinton “failed to protect her people on the ground ... We have to elect someone who will have our backs, won’t leave anyone behind. We have to elect someone who will lead with strength and integrity. And I believe that person is Donald Trump.”

“We did our part, now you do yours,” he said.

Trump, a billionaire New York businessman who also made his mark as a reality TV star, brought out some big guns from the entertainment world.

“We need a president who will have our back. No matter who you are, Donald Trump will have your back,” said Willie Robertson, star of the reality TV show, “Duck Dynasty.”

Throughout the convention, Republicans memorialized police shot by snipers after recent incidents in which police shot and killed African American suspects.

Republican National Committee Chairman Reince Priebus referred to “troubling times,” and held a moment of silence for the “genuine heroes” of law enforcement “and those who lost loved ones.”

Milwaukee County, Wisconsin Sheriff David Clarke, an African American, shouted “Blue lives matter,” drawing cheers and applause.

With Emily Ngo