Biden, the oldest-ever US president at 81, made the blunder as he ripped his Republican rival, former President Donald Trump, 77, in front of the star-studded crowd.
“We’ll certainly never forget the dark days of June 6, January 6th, excuse me,” the commander-in-chief said, according to a White House pool report.
“One of the dark days in history. The idea that wasn’t an insurrection — I don’t understand.”
June 6, otherwise known as D-Day, commemorates the allied invasion of Normandy, France during World War II, during which more than 2,500 American soldiers were killed.
Just moments before his latest gaffe, Biden had railed off a slew of Trump’s other apparent failures.
“We’ll never forget him wanting tear gas to be sprayed on peaceful protesters outside the White House, and holding the Bible upside down. Now he’s writing his own Bible,” he said.
The president also railed against Trump for “lying about COVID and telling the American people to inject bleach in their arms.”
“He injected it in his hair,” Biden quipped.
The fundraiser was held in the backyard of Douglas and Zeta-Jones’ riverfront home, where about 100 people sat under a tent to listen to both Douglas and Biden speak.
The Hollywood actor had noted his wife was absent because she was filming a new television series in Dublin, Ireland.
“Number 46 must become number 47,” the “Wall Street” actor said, referring to Biden as an “extraordinary, seasoned veteran.”
Biden joked that he had something in common with the Academy-Award-winning actor.
“We both married way above our stations,” he said.
Biden joked that he had something in common with the Academy-Award-winning actor.
Fashion designer Eileen Fisher; attorney Rodge Cohen and his wife, Barbara; businessman and venture capitalist Robert Goodman and his wife, Jayne Lipman; hedge fund manager John Shapiro and his wife, Shonni Siverberg; and Jonathan and Judy Siegel were all listed as hosts of the reception, along with Douglas and Zeta-Jones.
It wasn’t immediately clear how much Biden raised during the event.