Quote Originally Posted by k_raso
Does anyone has a "professional" knowledge on how to work a protectorate out of an enemy faction?

I mean:

Does devastating enemy fields help?
Blockading?
How frequent should you ask for it?
Does it mean anything that you send good dipliomats to ask for it?
etc...

I saw some guides some time ago, but they were made for 1.2 engine... something that has varied with the 1.5 update...

Cheers!!!
Well not "professional" but, I experienced this:
1 Nope - the AI doesn't really feel it
2 Nope - because the AI hardly ever cares about it; and in the case of ships you're most likely anihilated by some pirates that you annoyed in the first place by taking some Eleutheroi settlement
3 You shouldn't ask about it; they should be "asking" for a ceasefire; then you can counter offer to become a protectorate - which they may accept, also depending on the details of your offer (sweetners etc.).
4 Nope.

What really seems to work is anihilating their field armies and then besieging (but not assaulting) as much cities as possible at the same time. This effectively means that the AI isn't able to produce any more military anywhere near, and then it will try diplomacy instead.