Between the core rules and D@W, I think I’ve got a pretty good handle on how strongholds are build, what they’re made of, and how they fare when attacked. Settlements, however, are another matter.
At the abstract end of things, “Sieges Without Maps” (Campaigns 77) tells us that urban settlements have 1shp per 8gp urban investment, but I can’t find any indication of what typical town fortifications might be for sieges with maps. Does some fraction of the urban investment get used automatically for fortifications or are they completely undefended by default and the the lord must purchase defenses separately? Or do the townsfolk build defenses on their own, at no cost to the lord, as a side-effect of population growth?
What if the lord of a domain chooses to forgo a traditional stronghold and instead build up a fortified settlement as their stronghold? (This seems to be the direction my players want to go. Their “stronghold” is a kilometer-diameter ring of palisade with 10 watchtowers and 3 gates, which they then built a settlement inside of.)
nDervish, urban investment is kept abstract because otherwise it can get immensely complex. The town is assumed to be building defenses on its own, as a side-effect of population growth and investment, to the tune of 1shp per 8gp urban investment.
A lord who wants to build up the fortified settlement as their stronghold can choose to count his expenditure as either urban investment or stronghold value. Each has slightly different in-game mechanics. In-world, urban investment might be understood as a donation to the merchant’s guild with instructions to strengthen the city’s walls, while stronghold value might be the lord building a citadel or acropolis in the city.
For example: say you have a city with a maximum occupancy of 624. that’s 25,000gp which would be 3125 SHP, some quick napkin math tells me two gatehouses (2000 SHP), 4 stone buildings (800 SHP) and 300’ worth of battlement (300SHP) would get you pretty close to what might encircle the town (assuming I’ve correctly interpreted that a battlement is a kind of wall and not a wall accessory).
If we assume my guesstimation is typical (which is probably a bad assumption, but somebody with a better idea of medieval logistics could come up with a better spread), that stuff all costs 9,200gp, or about 37% of the total urban investment. presumably the other 63% is spent on non-fortification things.
As a nitpicky PITA, I feel compelled to point out that 300’ of battlements won’t enclose much area; a perfect circle of that size would only enclose around 1/6 of an acre, and even if you incorporate the gatehouses and buildings into the wall, it’ll enclose less than half an acre. For a Class V settlement like this, wood is probably more likely than stone for building material. Stone will be more for your Class I and Class II, maybe Class III settlements.
Two reasons why I didn’t just assume that was the intention:
It doesn’t always work out that nicely. A starting settlement is 10kgp, 1250shp. Campaigns lists two structures as having 1000shp: a gatehouse (6.5kgp) and a medium round tower (22.5kgp, over double the full cost of the settlement).
And the descriptive text for “battlement” describes it as “A defensive structure built atop walls to protect defenders from enemy fire.” So a wall accessory, not a type of wall. Add in 300’ of the cheapest listed stone wall (20’ high castle wall) for the 300’ of battlements to go on top of, and that gives you an extra 4500shp at a cost of 15kgp - it still fits into the gp budget (if only just barely), but it goes way over the shp allotment.
The settlement’s shp could come entirely from civilian structures. That basic 10kgp settlement can hold up to 250 families. Put each family in a 50gp mudbrick or wood hut, and that’s 500shp. Throw in some additional infrastructure (aqueducts, sewers, etc.), add a few richer families with 1200gp stone townhouses (100shp each), and you can easily hit 1250 or more shp with no fortifications at all.