Reddit reviews Castle Guide (Advanced Dungeons & Dragons, 2nd Edition, Dungeon Master's Guide Rules Supplement/2114/DMGR2) (Advanced Dungeons and Dragons)
We found 3 Reddit comments about Castle Guide (Advanced Dungeons & Dragons, 2nd Edition, Dungeon Master's Guide Rules Supplement/2114/DMGR2) (Advanced Dungeons and Dragons). Here are the top ones, ranked by their Reddit score.
Battlesystem in a nutshell: Take 10 (or more) NPC's that are essentially identical, like level 1 warriors, and treat them like a single creature with the same AC and thwacko, with with 10x the hit points and damage. Same mechanics, but you just divided the number of rolls you need to make a turn by 10. There are some other rules about morale and routing, blah blah blah, easier to handle that stuff by DM judgment IMHO.
If you want to look at large scale battles from a more distant perspective, the castle guide has a set of rules for handling battles with just a few rolls (roll 1d100. low roll, side A takes losses, loses morale, side B gains morale. high roll, side B takes losses, and loses morale, side A gains morale.) with modifiers for things like leadership, magic, or scary monsters.
You might be really interested in a 2^nd edition book called "The Castle Guide." The title is a little misleading as it does talk about land types and values, upkeep costs, potential incomes, build times, manpower requirements, etc. The only caveat is that this is based on a 2^nd edition economy, so you might want to adjust gold values slightly, but things like manpower and build times should remain the same.
Strongly suggest DMGR2 : Castle Guide. TONS of good data. You can purchase or get PDF online.
https://www.amazon.com/Advanced-Dungeons-Dragons-Dungeon-Supplement/dp/0880388374
Chapter 5: Castle Construction has everything you want.