Because of how Mattis is viewed within the military, the timing and forcefulness of his criticism of Trump are gargantuan. Mattis had dropped hints, but lulled us all into believing that he might never speak out directly against Trump. Among rank-and-file service members who support Trump, Mattis’s silence was seen as an implicit endorsement of this administration’s actions.

So Mattis’s comments came as a shock. For the past two days on social media, veterans (and a few active duty personnel) who are normally die-hard Trump supporters expressed confusion about which leader to follow.

Mattis’s more significant impact, though, will likely never be seen. The officer corps—from company-grade officers to four-star generals—take their cues from Mattis and others like him.

In recent days, several former four-star generals and admirals—previously silent on Trump and the danger he poses—have spoken out against this administration’s actions. The DoD’s decision to withdraw the 82nd Airborne Division from Washington might have been driven in part by the pushback of Mattis, retired Admiral Mike Mullen, retired General Martin Dempsey,retired Marine General John Allen, and others.