If the fief is in rebellion and you are in the fief with troops, you use this option to attempt to quell the rebellion. In effect, a "Quell" is the same as a "Pillage".
You need an army to do quell a rebellion, at least 100 troops. The minimum ratio is one soldier for every eighty people in the fief. The more troops you have the easier it is. If you don't have enough troops, the locals will throw you out to an adjacent fief and you'll have to march back in and keep trying until you succeed. A success is equivalent to a pillage. That is, you make some money, but do some damage to the fief in the process.Note that what you call pillage today, was extortion then. What we call pillage then you would probably call atrocities today. We don't rate stature as historians but as contemporaries would view it. This is why the pillager losses stature when pillaging. (There is no stature hit if the fief you pillage is of a different language than your PC's.) The English funded the war for many decades through extortion and conquest (siege). Pillage is counter productive as it destroys the wealth you seek to exploit. The fought over parts of France were not destroyed as the Rhineland was during the Thirty Years War. Most of the brigands stole and extorted.
The noted English mercenary Hawkwood, for example, was a businessman, who was out to get rich, not kill the geese that provided the golden eggs.Quell By Bribery
For megafief owners, there is another way to quell rebellions. Instead of raising the troops needed for a rebellion, you can use bribery. This works as follows; for every stature point the megafief owner has above five (stature rounded to the nearest whole number) you need twenty percent less money than if you had raised troops (at 1,200 ducats a soldier) to quell the rebellion. Normally, this would work out to 15 ducats per person in the megafief. If your megafief had 500,000 people when it rebelled, this would normally cost you 7.5 million ducats. If you stature was 8.6 (which rounds up to 9) you would need 80 percent less, or 1.5 million ducats. If your stature were only 5.7 (rounded up to six), you would need six million ducats.
Stature Ducats Per Person in Fief
5.5 or less 15
If you are short on stature and cash, you can take the chance that your "quell by bribery" will fail, with each stature point you are short equaling a 20 percent chance of failure. Thus if your stature were six and you needed six million ducats, but only had 4.5 million, you could go ahead anyway and have an 75 percent chance of success. One advantage of quell by bribery is that no damage is done to the fief. Note that this approach is only possible with megafiefs because these megafiefs are actually large collections of regular size fiefs with many contending nobles who, through the application of bribes and cajolery, can be calmed down without force of arms.