Thanks Zild, that seems to make sense.

I recall one attempt that I ended up aborting, due to the "he now asks for X amount" (more) and that's the end of that mission. With only one Em, that's also the end of that year and, sometimes, timing is everything.

I pulled off a successful bribe earlier but the circumstances were slightly unusual and it took two goes, mainly down to misunderstanding on my part.

1) They have a large 'outdoor' stack and a medium 'indoor' stack, in the castle (with ringwall, of which more later).
2) I set up a bribery mission on the large outdoor one.
3) On the same turn I launch an attack on the province, so I'm half hoping that the bribe is resolved before the battle and the resultant outnumbering makes it an instant retreat to castle type thing.
4) It isn't. The battle needs to be resolved first.
5) Battle setup screen. I realise I forgot to bring my spear units with me - whoops! I plough on regardless.
6) Fun battle but I'll spare the details for 'Pics & history..' thread.
7) Battle won, enemy remnants in the castle.
8) Return to Strat map, Bribery mission goes ahead. I expect the asking price is for the now wrecked units I've just sent packing, so I cancel it.
9) Next turn, siege is in progress, asking price still around 1500 for mostly armoured Slav Warriors and humdrum stuff but the amount of buildings, including swordsmith, port, trade post with two tradeables (Kiev, linking immediatedly to my trade network), farms+, not to mention the castle itself made it an absolute bargain, especially if I can avoid both assault losses and building damage.
10) Activate bribery mission. End Year
11) Siege attacker/defender losses are registered, seeing as I didn't order assault.
12) Bribery mission resolved last but I get a message that the price has been reduced. Obvius cause but I bet you don't see that one often. Someone at CA had their thinking cap on that day, though.
13) Bribe is accepted, territory taken, all buildings intact. Province income about 908 p.a. total, with 470-odd in trade.
14) The 0* general who was in charge of them has 'Good Runner' plus 'Weak Principles', -20% to bribe but lack of checking beforehand means I don't know if he has just acquired EZbribe as a result of my mission or if that's what made it so cheap to begin with. Good though, innit?

He's Steppe Cav with only 6 men, so he's getting disbanded straight away. I'd disband the lot of them and be content with the building costs saved only most of them went straight to 5-6 shields on the loyalty scale. Amazing what effects cash can have.

Re: Castle & Ringwall. My spies have only just come online, with nil stars. I tested the first of them on the siege-in-progress and he was given a probability of opening the castle gates of..... 0%. Zip, zilch, nada.
I would have bribed anyway but this was the real clincher.