HISTORYPOST INCOMING -- STAND CLEAR
As for the Marquis, he's clearly a military prodigy, akin to this world's Hannibal or Alexander. Repelling an invasion from a rival power at only 21 years old is truly remarkable.
It's not really clear that this is true, at least not to the extent represented here. There are a largish number of successful commanders from pre-modern times who started in their teens or twenties and had considerable success around the time they started; a large number of the tasks involved in successfully leading a (pre-modern) army lend themselves well to aptitudes rather than skills. The reason it seems weird to us is that we very seldom have reason to put a young person in charge of an army today, and in fact doing so would be taking on a large, avoidable risk. (Since randomly selected people with limited skill development *aren't* usually talented, and the lack of experience means that we lack a particularly good filter for sorting the untalented majority from the talented minority.) Aristocracy sidesteps the problem of reluctance to giving unqualified people commands. :D More signiifcantly, being a commander in a setting where your enemies also are working off an aristocracy makes it
much easier to stand out as an exceptional commander, since the likelihood of the opposing commander's incompetence is higher.
The French army at the end of the 17th century boasted, at least according to their records, 400,000 men if I'm not mistaken. Which source are you citing?
Here, I'll link a paper by John Lynn on the size of the French army in that era.
http://www.reenactor.ru/ARH/PDF/Lynn_01.pdf
It's worth noting that Louis XIV was an aberration of his time in many ways, including this one. Moreover, the 16th to 17th centuries saw unprecedented development in real world militaries (the "military revolution" alluded to in the paper), and as it notes, the largest French force mustered prior to 1632 was less than 75,000. My impression is that the setting we're in is multiple centuries older. So a question that may arise is, was the growth of militaries in that era a coincidence, or was it logically contingent on technological, social, and political factors that didn't exist until the mid-17th century? I'm inclined to guess the latter; a kingdom fielding 6-figure armies for anything outside an existential threat probably requires a few things to be true:
a) Infantry needs to be useful in a way that scales. (There aren't enough horses.)
b) Unarmored or lightly armored troops need to be useful in a way that scales. (There isn't enough armor, either.)
c) For the above two reasons, you probably need them to be using ranged weapons. And you probably need the ranged weapons to be firearms. Why? Training 125k dudes to do anything is pretty hard. It took a
long time for firearms to strictly outperform trained archers (there's a famous example of the Duke of Wellington asking for a company of longbowmen during the Napoleonic Wars), but it is vastly easier to create a useful soldier in a few weeks or months if you're teaching him to shoot a gun than a bow, or (god forbid) if you're giving him a melee weapon that you expect him to wield in limited armor without shitting his pants.
d) There's some thought that improvements to fortification technology consequent to early artillery resulted in a siege-based style of warfare, which meant it required more manpower to run a war than was previously the case.
So there is some historical basis for believing the logistics represented in this game about demon tits might not have 100% verisimilitude. I recommend not caring about it. In conclusion, B1, making our dude murder his own men for the love of our depraved pet genius is cool.