Two new islands. The Old Fort founds a town inside somebody else's walls, one gateway in them, and the dead marching at it from a Necropolis in the far corner. Break the Necropolis and the island is yours.
The Last Ground gives four bands no town at all and a tide that takes the island out from under them. The three rivals now play it rather than drown in it.
Two feats to go with them, and every wall stands the right way round at its corners.