To battle it is then, sire.

In this screen, we can press 3 buttons. The button on the far right is used to break off sieges, just in case some huge army is barrelling down your way. The button in the middle is the assault button, which everyone needs to press once in a while. The button on the far right is the maintain siege button, which starves out the blockaded defenders. This is very handy for reducing the enemy combatants numbers or forcing the enemy to attack you, abandoning their defensive position.

But screw that lets just kill those bloody bastards already.
Our general provides a rousing speech of how he doesn't needlessly throw lives away and that if all do their part victory will be theirs. He comes of all noble and chivalrous too when he talks about valour or something, I don't know.

We start the battle by doing the only thing we can do with militia,
needlessly throw their lives away. Our archers are hiding behind a building, peppering the enemy's reserves while our mob of spears clash against the enemy like a tsunami on an ocean rock.

...providing the perfect distraction for our heavily armoured death machine of a councillor and his bodyguard. Of course, the AI in this game is severely lacking, and the cavalry charge forget to drop their lances on the first charge, effectively throwing
yet more lives away, needlessly.
Well, unless you're a peasant with a bow.

Very quickly, the enemy forces melt from the combined spear mob and cavalry charge, although at heinous costs to our ranks numbers. I'll admit it now: I'm a terrible street fighter. Also, for some reason the enemy killed 70 of our dudes but we only lost 68. Fucking magic, man, how does it work?

Now that the settlement is firmly under our control we have the options of occupying it, which peacefully takes control of the settlement with no harm done.
Then we have the option of sacking the settlement, which involves looting and raping everything.
Finally, and most grisly, we have the option of exterminating the settlement, which is pretty much fucking killing everyone.
In my opinion it is better to exterminate, if you don't care about foreign relations.