The US military also has floating nuclear power plants capable of powering entire cities in an emergency. They used one in Banda Aceh after the tsunami. Other combatants prefer not to mess with the lights.

From the 8 year old knowledge I was told by someone in said industry that worked on government nuclear projects..

These mobile nuclear power plants are transportable via classic steel rail way. The reactor is about the size of a normal train car. (Although I'd guess there are many accompanying components too.) The fuel is typically enriched nuclear matter in ceramic like pellets.

A single car of unspent fuel can power NY City for a month.

Big populations impacted that depend on electricity for food, water, and waste will receive these before rural populations.

I'd be interested in the restrictions to the public in such circumstances. Rationed EV charging, no home A/C usage, community cooking centers.

The US is a bad example in this case because it hasn't really fought wars with equal powers except for total war during WWI/II. Even the Civil War was largely an asymmetric conflict. General Sherman could destroy rail and other industrial infrastructure because the Union had industrialized so much that they could restore anything they needed relatively quickly with parts and equipment brought in from the North. During the World Wars, retreating German troops would often go scorched earth on their own infrastructure to prevent the advance of the Allies as a last ditch attempt to slow their losses and come to a more favorable conclusion that total defeat.

In the case of wars in the last 30 years, the US military has operated on a shock and awe strategy followed by nation building. The former encouraged destroying (or crippling) power generation to cause chaos and the latter is very lucrative to American companies that come in to build the power generation afterwards. Since the US military has absurd resources, bringing in portable generators by the thousands (along with the fuel) is also easier than having to deal with existing infrastructure that was already decaying and incapable of properly supporting their logistics. During the wars in Iraq and Afghanistan, many of the power stations rebuilt by the US were never used, even for the military, and sit idle to this day.

To be fair, we didn't have an electricity grid when we had our civil war. ;-)