<For whatever unfathomable reason, the Left destroyed our early Civil Defense programs.

"Our early Civil Defense program" consisted almost entirely of holes in the ground, such as SDAI uncovered in what used to be my hometown newspaper (I went to high school with kids from Levittown, PA; we heard rumors of fallout shelters but never knew where any were). CD in the States was always an individual effort - the Feds printed and distributed leaflets with suggested home shelter plans, and distributed them to (among others) grade school kids. As far as I know, there was never a serious suggestion to follow the lead of Switzerland - that is, a massive, publically-funded infrastructure - and to do what those Commie countries were doing??? ...well, maybe you remember those days, too. Did your parents fall for the Big Lie of survivability, at their own expense? Mine didn't...

Yes, there were designated "shelters" in large public buildings in urban centers - once in a while you can still see the old black-and-yellow signs. Ever been in one? I have, more than a half-dozen, in the course of preparing to design renovations. They were, simply, the basement: no properly-filtered ventilation; unsealed windows; standing room for a few dozen people wedged in among the obsolete textbooks and PTA meeting minutes. Off in a corner were a few tin-plate barrels marked with the old CD logo. The ones for water were empty; the ones that allegedly contained food were full of packaged saltines, if vandals and/or vermin hadn't gotten to them.

National civil defence always was (and technically still is) deterrence.

I dare say few people know what they should do if they are in the path of a radiation cloud, either from an attack, or from a nuclear accident.

The short answer to that is the same as it was in 1960: listen for instructions from the Emergency Broadcast System (the successor to Conelrad). People who live near nuke power plants are allegedly protected in an 'event' with warnings and evacuation plans (soon to be augmented with iodine supplements?) - but perhaps Mary Anne may want to address that better than I ever could; she's an isotope's throw from TMI.

The resulting unnecessary deaths could probably be laid directly at the door of the 1960s anti-war movement.

I suppose they could, if you were looking for straw men or scapegoats. More likely, the deaths would be due to lack of warning, panic, inadequate roads, more panic, unavoidable direct exposure, and even more panic.