Also, I've also now had swamp troops spawn in one of those raid thingies and attack my beach house in the meadows, so I'm pretty sure the strength of those things is dependent on your progress through the game.
Fortunately, they spent their time attacking the fences around my little patches of mini-farm. Unfortunately, they slaughtered all my piggies
Fortunately, I was barely even bothering to feed the piggies anyway, so that's kinda NBD. There was one skeleton in the water though shooting arrows at the temporary raft I'd built to be able to build over the water a bit, so he got an arrow in the knee.
I think my next base is going to be on a big raised pillar of dirt or something, way up off the ground. Yeah, it's probably not going to look as neat as a giant freakin' castle, but in a game that's otherwise pretty cool in eliminating a lot of those annoying mechanics that have become staples of this sort of game - that "random spawned assault" to make you run around repairing things is one that still annoys me.