LONDON — One after another, women rose in Britain’s House of Commons and pleaded with Prime Minister Boris Johnson to stop calling his opponents traitors, lest a madman take his words to heart.

But time and again on Wednesday night, Mr. Johnson pulled new slurs from his lexicon, accusing those who disagree with him of humiliating Britain, surrendering to Brussels and betraying their own constituents in phrases that evoked war with the European Union, not a wonky three-year negotiation.

As rowdy as Britain’s Parliament has been in recent months, Mr. Johnson’s eruptions marked a new front in the culture war over Brexit. Especially for the roster of women in Parliament who begged Mr. Johnson to calm his incendiary language, the outbursts were chilling, exposing the vitriol within parts of the Brexit project and the nastiness that lawmakers say Mr. Johnson has often reserved for women who stood up to him.

The prime minister’s remarks dampened hope of opposition lawmakers voting for a revamped Brexit deal and stirred alarm across Europe, where diplomats despaired over the prime minister’s bellicose tone and warned of his words’ fueling political violence.