The call to arms came in the form of a memo.

Marjorie Pritchard, the deputy managing editor of The Boston Globe, reached out to editorial boards at other newspapers last week.

“We propose to publish an editorial on August 16 on the dangers of the administration’s assault on the press and ask others to commit to publishing their own editorials on the same date,” the memo said.

As of Tuesday, more than 200 newspapers, including The New York Times, had signed on.

The Globe’s effort to rally editorial writers across the country came in reaction to the president’s stepped-up attacks on the media.

At a recent rally in Pennsylvania, Mr. Trump pointed to the group of journalists covering the event, saying they “only make up stories” and called them “fake, fake disgusting news.” On Twitter, he has revived an old phrase — “the enemy of the people” — to describe “much of the media” and “the Fake News Media.”