I was an almost 18 college freshman and had driven a car load of folks home for Easter in the D.C. suburbs in Maryland. Got within a few blocks of the house and couldn’t get off the Beltway because troops from Ft. Meade were using New Hampshire Avenue as their route into D.C. Everybody else got out of the car and walked the rest of the way.
My recollections: When General Westmoreland returned (was recalled?) from Vietnam he was given command of the military district encompassing D.C. Given the threats of riots/insurrections, he requested some impossible number of troops (250,000, IIRC) to handle the possibilities.
I was in a battalion of combat engineers at Fort Belvoir and we were given something of a first-response, riot-control duty for the D.C. area. We weren’t involved in what you relate but were at the Pentagon in October of 1967.
Anyone believing the country is some sort of tinderbox today has forgotten the situation in the latter 1960s and the 1970s.