How many castles do you need?

[Marshal Murat]

I've heard several opinions about the amount of castles you should have.
On one hand, there are posters who say
1 castle, the rest convert to towns.

My personal dogma is have 2 castles, one on each border (east-west). Like to think of them as bulwarks of the nation,the rock that the enemy shall dash themselves upon. Provides quick, heavy, advanced units for combat, right to the battlefield.
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Of topic, can you switch into eras?

[Quillan]

It depends on the faction, too. Most of the time, I try to run about a 1:6 ratio with one castle providing heavy troops for all surrounding provinces. Occasionally I'll have more or less. I ran the first part of my Venice campaign with only one castle, even when I had close to a dozen provinces, because Venice and Milan can really get by with city troops only for a while. It wasn't until I needed good infantry that I started with castle troops.

[Nutranurse]

Meh, I like to specialize. I have a couple castles dotted across my Kingdom, all strategically placed of course. They, however, do not serve as walls really, I have forts for that, the castles just produce certain units.

E.G. On my French Campaign I have two castles near my France-Rus Boarder, one of them produces great cavalry thanks to the Horse Breeder Guild the other makes Much needed infantry. Both of hte castles are spec'd to produce the best units possible in their respective fields.

[Sir Boo]

Well for a general rule of thumb have at least 4 more towns than castle if mainting a large empire. Now i play the HRE in my campaign "controlling France,Milan,Scilliy,The Pope,England,Scotland,Denmark and Spain" I feel that you can have as many casatles as you want however the placement needs to be corect. For example when i invaded France i had 2 castles built on the border , pumping out armies. When i finally pushed into spain i took 3 settlements in 2 turns. Now i kept the 2 castles and still pumped troops into the regions untill i reached the moors and wiped out spain. Now i converted both castles into towns and started again on the moorish border. I belive this in my view is the right tactic however it can be costly so its advisable to have a good rich income before trying this method.

[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.