Not even Queen Elizabeth II was spared.

Prime Minister Boris Johnson was accused of provoking a constitutional crisis. The opposition was denounced as ignoring the will of the people.

Almost no one in Britain seemed able to avoid the debate about Brexit, seemingly louder than ever on Wednesday, as accusations, defenses and counterattacks ricocheted around social media.

The barrage began in the morning, after Mr. Johnson announced that he would limit the time that Parliament has to try to prevent Britain’s withdrawal from the European Union without a deal.

He was immediately assailed by critics, and defended nearly as quickly, exposing the deep divisions that over three years of debate about Brexit have failed to resolve.