Amid the silent sniffles and eye-dabbing last week as four policemen recounted how they struggled to hold off the howling pro-Trump mobs on Jan. 6, a significant anecdote told by one of the officers drew no attention from the presiding committee members or in the following days’ news accounts.  

Capitol Police Officer Harry Dunn recalled how at 10:56 am on the morning of Jan. 6, he got a text message from “a friend” who had acquired or overheard a detailed plan by one of the militant groups for a coordinated, military-style assault with guns on  the Capitol.

“Seeing that message caused me concern,” Dunn said—an understatement considering what soon followed. He added:  “At the time, we had not received any threat warnings from our chain of command. I had no independent reason to believe that violence was headed our way.” As it turned out, the Capitol Police’s intelligence office had plenty of warnings that something bad was af…