What I am going to confer to you is the greatest move that I have ever executed on a campaign map (and this is comming from someone who played TWs ever since Shogun). As a result of this move (or a small series of inexpensive moves) I destroyed a faction, brought the level of happinnes in my recently captured towns up, captured two settlements, and gained a hefty sum from sacking a large city. And all without losing a single soldier.
So I am playing the campaign as Venetians. I am in my 63rd turn and I am no. 1 in every category. I have lands in the Balkans and Outremer (which will soon be visited by Mongols as I see them stroking their whiskers on the edge of the map).
At this point I am on the verge of destroying Byzantines who have only two provinces left. They are left with Cyprus protected only by one unit and Nicea with two and a half full stacks. It would take me, in estimation, about 4 turns with heavy costs and losses. One of my armies is ready to assault Cyprus castle, as it has been besieging it since the last turn. I have a full stack of good quality units approaching Nicea. AI, as it sometimes does, moved the full stack of units with a family member out of the city only one square away, leaving only a king inside the walls. Working in mysteriously murderous ways, my most elite assassin is just in reach of Nicea.
This is how it played out: I first assaulted Cyprus and, because I faced only one militia unit, without losing a single soldier I captured it. Then I sent in the assassin who killed the king. The city was empty, so I sent my family member governing in Constantinople to purchase a mercenary galley to ferry him across that he may claim the city without any effort. I did not even have to engage my full stack army. Suddenly all their agents were wiped from the screen and armies faded grey. Byzantines, those dogs who were the first to lay their sword upon my possessions, tasted the bitter blade of that very sword. They were the first to attack me and finally met their just end.
In one fell swoop!