Remember Monday? It was four days ago, but it could just as well be four years. That day, in what was expected to be the big news story of the week, former Acting Attorney General Sally Yates testified before a Senate subcommittee about her knowledge of Russian interference in the 2016 election.

Ms. Yates recounted how, only days after President Trump took office, she rushed to the White House to inform Mr. Trump’s counsel, Donald McGahn II, that the national security adviser, Michael Flynn, had lied to Vice President Mike Pence and others about his conversation with the Russian ambassador. Ms. Yates testified that Mr. Flynn’s behavior exposed him to blackmail.

“To state the obvious,” she said, “you don’t want your national security adviser compromised with the Russians.” Despite the warnings, Mr. Flynn kept his job for 18 more days and was forced to resign only after The Washington Post reported his lies to the vice president.

Other events have since taken over the national consciousness. But in the aftermath of President Trump’s stunning move on Tuesday to fire the F.B.I. director, James Comey, it’s worthwhile for Ms. Yates’s successor — Deputy Attorney General Rod Rosenstein — to recall the courage and integrity she showed in those chaotic days of late January, when her superiors demanded only loyalty.