DUBLIN — That didn’t last long.

Joe Biden managed to tread carefully around historic and current political sensitivities during the first part of his trip to the island of Ireland this week, marking 25 years since the U.S.-brokered Good Friday Agreement sought to secure lasting peace for Northern Ireland.

But not long after crossing from that U.K. region into the Republic of Ireland on Wednesday, the U.S. president made a major gaffe: He confused New Zealand’s “All Blacks” rugby team with the notorious “Black and Tans” British military unit that fought the Irish Republican Army a century ago.

At the end of a rambling speech in a pub Wednesday night, Biden — flanked by Irish Foreign Minister Micheál Martin and star rugby player Rob Kearney, a distant cousin — tried to pay a compliment to one of Kearney’s greatest sporting accomplishments. That would be when Ireland’s rugby team defeated New Zealand for the first time in 111 years, in November 2016 in Chicago. New Zealand’s squad is famously called the All Blacks, in reference to their uniforms.

Trouble is, Biden let slip a reference that could well reflect his affinity with Irish rebel history and its folk songs.

“He’s a hell of a rugby player, and he beat the hell out of the Black and Tans,” Biden said to audience laughter.

The Black and Tans were an auxiliary unit of Britain’s security forces that fought IRA rebels in their 1919-21 war of independence from Britain. Their name reflected the improvised and inconsistent colors of their uniforms.

The unrelentingly pro-Biden coverage on state broadcaster RTÉ, which televised his speech live, didn’t acknowledge the mistake. The commentator’s sign-off? “Well, that’s Joe Biden: a little bit sentimental, a little bit schmaltzy, but a thoroughly decent guy and a great friend to Ireland. The trip is off to a great start.”

But the gaffe and “Rob Kearney” blew up on social media in Ireland. Some listed the retired rugby fullback’s career accomplishments including, most famously, his single-handed defeat of the British forces a century ago.

“The greatest gift Ireland wanted from Joe Biden was a signature gaffe. And … didn’t he just go and give us one for the century,” tweeted comedian Oliver Callan.

Lost in the shuffle was Biden’s other Kearney gaffe: He still hasn’t figured out how to say his name.

When introducing Kearney at the White House on St. Patrick’s Day, Biden called him Keer-ney. The Irish pronounce the name Kar-ney. Biden stuck with Keer-ney on Wednesday.