Being a merchant of death, you may be interested to know that the consumers of your products have turned the consumption itself into a science; yes—the art of siege warfare, though hardly new to your medieval customers, since it was inherited Assyrian and Biblical times (as early as c.900 B.C!), your customers had a unique formulation of the deadly art of laying siege. It was called “poliorcetics.” (Now, try and stop thinking about the disease called Polio and try and move on with today’s lecture.)
I suppose that it is natural that a science of siege warfare developed. With castles and fortresses controlling the country side, and the actual act of laying siege a heavily political affair which consumed resources, the practice of capturing said fortresses, through political or military means, would necessarily involve intricacies which demand a specific form of engagement. I guess that simply throwing massed reams of men at a stone wall wasn’t enough, eh? A science needs to be involved. Who knew?
Castles, of course, were more than mere fortresses, they were also the residences of their lord. This would be a distinguishing mark; Anglo-Saxons, for instance, had primitive castles but these were communal burhs inhabited by war-bands. Later on, the Tudors would build castles which were purely defensive measures; medieval castles were a combination of the two: they provided residences for the soldiers and kings, but weren’t homes, per se; likewise, they provided defensive structures for a given territory which acted both as an economic center but also as a means of domination for that particular geographical locale.
So, it could be argued that because of this dual nature, an equally dual science of capture was demanded, hence the diplomatic and military intertwined when regarding castle capture. At any rate, your subjects have castle capture down to an art. So… try and pander to that art? Point is, you need to step up your game and sell some more death; we have a deadline, mister, and you’re not pulling your weight! (and take that hippy peace sign off from your scythe!)