This was my original notes for the story, many of which are now obsolete, but I'm posting them anyway, I'll put up the rest of my notes at some point soon.
A feudal system with Napoleonic technology, but more importantly, the necessary politics. Pressure on nearby neighbours from an expanding force nearby. Similar to Peninsular campaign, but the Mark - realm of the Marquis, the homeland of the subject characters - is not a separate island, tempting as it may be, but a peninsular itself. There is a growing political pressure that leads to a dispatch of a campaign force. Need to differentiate from sharpe somehow; well for starters there's flying machines, airships and perfect plywood constructs.
needs more, then a start. The story will eventually lead off-world, and the forces of chaos will be personal and internalised in their evil, subtle in fact; and the Marquis has a small caché of lasguns and other holy relics. The relationship of Imperial creed to the world, and the relationship of the Imperium as a whole, is distant and mysterious. The Imperial monks resident at his capital will be decendants of the original missionaries, derided as crazy.