Civ 5

[Jackalope]

As far as online guides go, I've read some pretty questionable crap in them - like for instance, I read in one that the author thought that submarines were useless on offense.

To be honest I didn't see the need in subs when I used them. They actually were pretty pointless. I wonder if it's because your version of the game may be different? You know when you were talking about caravels and ships taking cities? That just doesn't happen in my game. There's no concept of a 'melee ship' when I play, I've tried numerous times to take cities with ships and it just doesn't work.

I have the Gods & Kings expansion, but not Brave New World. As far as I know, the mechanics haven't changed.

You gotta beat 'em down with ranged units first, and swoop in once they've been beaten down to zero or near zero health. I don't do this until I have privateers, and I give them the promotion that gives bonuses to attacking cities.

Submarines *rock* at ship-to-ship combat - with two promotions, you can one-shot or almost one-shot almost anything except ironclads, missile cruisers, and destroyers - and they can't see you (except for destroyers, missile cruisers, and other subs), unless they're immediately adjacent to you. Nuclear subs can carry missiles and nuclear missiles. If you get to subs first, seriously, you can absolutely *own* the seas to the point where you're not at risk of anyone even setting foot on your land from the sea.