On the defensive side:
- Never less then 1 unit per city, and I much prefer 2 units per city because it gives me the ability to pull the 2nd defender to respond to emergencies.
- Early on, 1 archer 1 axe 1 spear in border cities. The axe and spear are often optional. Inner cities are typically only 1-2 units. Risky borders with aggressive neighbors will have 4-6 units including horses. These extra units can also be called up to form a SoD for attack.
- I'll usually form up my SoD at a place where it can reach the border cities within 2 turns. Usually inside a city, but sometimes on a fortified forest/jungle hill position.
- After 1000 AD, defensive size depends on what size stacks I see floating around inside my aggressive neighbor's borders. If I see a stack of 20 attackers, then my border cities had better have a permanent force of 6 strong defenders, with a floating defense that can boost an individual city up to 16 defenders in a jiffy. If I have next-gen units over their attacking units (infantry vs muskets), then I'll only need about 1/2 of their numbers.
- Either way I prefer a permanent force of 2-4 decent strength defenders in most cities. Preferably one of each type defender (anti-melee, anti-archery, anti-air, anti-tank, anti-infantry, anti-seige, anti-mounted).
- If you have BUG installed, I try to always keep my military power at 0.9-1.2 of the most powerful AI civ. Anything under 0.8 and you risk getting attacked too often, anything over 1.2 and you can probably shrug off any attack as long as your units are positioned well and modernized.
- Always have horse units parked on hills with +1 sight along dangerous borders. They're sacrificial lambs to show you where the SoD is entering your borders from.
- I always put Triemes out in packs of 3, which pretty much holds true for all of my naval units up through Destroyers. One unit can easily be overrun, 2 units is iffy, but with 3 units you can have 2 strong defenders and a medic. The trio of ships won't stand up to a full fleet, but can handle non-stop action for a very long time against solo attackers.
- Only strategic sea resources (oil) get defended with a decent pile of units. Minimum of 3 destroyers, later beefed up with 2 subs and 4 battleships. Food resources might get a token destroyer or submarine, more to serve as a tiny deterrent or warning.
- I typically also put out a screening force of subs away from the coastline at intervals designed to alert me to incoming naval threats.
On offense:
- I don't go to war unless my power rating is at least 20% higher then the opponent. Unless I've recently researched a tech that gives me a huge jump (such as when Infantry/Cannons enter the picture).
- My SoD in mid-game (cannons / infantry / cavalry) is typically at least 6-10 cannons, 4-6 cavalry, 6-10 infantry. Plus 2-4 infantry per city that I'm going to take and hold (garrison forces). So a stack size of at least 20 units and preferably closer to 30 units. If I have spare units, I'll open up a 2nd front against a weak enemy and go after their less defended cities on the flank with a smaller force of 10-15 units. Figure that I'll lose 2 siege per city attacked along with 2 infantry. For an extended campaign of 10 cities to be taken, that means 20-30 cannons, 8-12 cavalry, and 30-40 infantry.
- A modern naval SoD needs to have 3-6 destroyers, 2-4 subs or attack subs, 4-8 battleships, and 2-4 carriers. And as many transports as I think I'll want (usually enough to move a stack of 30-40 units). The goal is to be able to stand up to an enemy SoD and be able to handle a mix of threats without becoming too weak after losing a few ships.
