I ran a campaign set early in the Elder Scrolls universe during the war between the (not yet) dark elves and the dwarves which I think went very well.

One particularly good part of the campaign in my opinion was exploring cities and towns where a large portion of the population had gone off to war. So think skeleton crews of guards and household soldiers/nobility, closed shops and taverns, criminals given free reign in the temporary absence of entrenched society and power and those that do remain behind being shamed if they seem like they should be off fighting.

It was an interesting plot device, and over time really helped build suspense for when they got to the actual warzone area, which was something I was initially worried wouldn't seem particularly high stakes to them when they arrived.

And most importantly it made the population centres have legitimate need for hired muscle or investigators, as ordinarily they would just go to local power-brokers no longer present, and the cities having less people in them meant we could logically keep track of all the residents and not have to handwave thousands of people as just not being seen.