I was watching Band of Brother and wondering how those paratroopers got letters from home. Did their family need to know their nearest base? Or could they simply write their name and battallion? If I want to mail a package to a sailor do I just the ship’s name? Or a port? I’m not actually mailing anything I’m just curious how that works. How much postage do you need to mail to a ship overseas?
It’s actually kind of neat. They have their own “state” codes for the Air Force or Navy, and that’s how the mail is handed over to the military. They do have to give an apo or the like, but the deployed know that before leaving so family knows how to write.
It gets murkier once it’s inside how they route the mail, don’t know for sure, but as long as you follow USPS guidelines it’ll get to them. So, part of your answer at least
https://pe.usps.com/text/pub28/28c2_010.htm