How many castles do you need?

[Shahed]

Playing Turks, the only castle I have are Yerevan and Ragusa out of the total 43 regions controled so far.

[Quillan]

Turks can produce Sipahis in cities with the racetracks, right? Again, it's a case where they aren't really necessary for troop production.

[Shahed]

Correct. They can produce Sipahi and Turcomans from racetracks. The Turks have a lot of city troops, the only reason I'd want castles are for Kapikulu, Dismounted Sipahi Lancers, Ottoman Infantry, Javelins and maybe Naffatun. The Turks can get by with cities, specially playing all cavalry, only your heavy lancers will come from the castles. And actually I just checked and I also have another castle.

So 3 of 43.

[gingergenius]

My English campaign that ended in world domination had a policy of 3 castles, but that distorted later on. I had Bern, Staufen and Innsbruck as my 3 when I was fighting against Italian and Eastern Eurpean factions - but later on they were too far away so I just kept Innsbruck. Due to the Timurid threat I made castles in Mosul ane either Edessa or Damascus (can't remember). These provided me with enough Retinue Longbowmen to defend the bridge over the river to the west of Baghdad.

In the Americas, Caribbean (Habana) looked like a good place to base a castle as it had no resources to trade. In the end I didn't need it, having sent over 4000+ mercenaries and generals to defeat the Atzecs, recruiting more local mercenaries.

Call me boring but I've started another English campaign, this time as a short game and focussing more on diplomacy etc. I've kept my castles in Nottingham, Caernarfon and Caen, as there are Scots to the North, loads to the South, and I haven't bothered to change Caernarfon just yet. I also want a woodsman's guild in Nottingham.

[Quillan]

If I were playing the English, I'd probably convert Caernarvon and Inverness once I'd conquered the Isles completely. I'd leave Nottingham in order to produce castle troops back home still. That way I could use them for naval invasions or reinforcements on the mainland as need be, and they'd be close enough to not require many turns to get where they are needed. They also make a decent fallback if events push you off the mainland (possible in the early going if you get gang tackled by France and the HRE or Danes).

[katank]

There isn't a set number. Really depends on your faction. Italian factions, Egypt, and the Turks can get by with very few castles (2 or 3 in a large empire of 30+ provinces).

For other factions, I'd say anywhere from 1/7 to 1/4 of your total territories. Specialize them for troop production (infantry, ranged, cavalry etc.)

As for the defense bit, I think that huge cities are actually better right now due to the fact that a city's cannon towers aren't bugged. Citadel's cannon towers only shoot ballista bolts.

[PaulTa]

Well it definitely is faction specific, since some factions make most of their best units from cities (Spain, for instance, get's gendarmes, tercio pikes, and musketeers from cities).

Generally, I see it like this. The only economic bonus that a city has over a castle is increased trade. If the city is constantly under siege, then the trade bonus is null anyways. Since the settlement is constantly under siege, that means that it's in my war zone, so I'll lean towards castles.

Then again, there is an exception to that as well. Occasionally it's nice to have a castle on an island or by water for quick sea based reinforcement. In some cases, border cities generate way too many florins to be converted in to castles (like vienna for germany early on).