epicivfreak
Prince
Roman forts along Hadrian's wall in northern Roman controlled Britain drew lots of people to them, prostitutes (soldiers needed something to do when not soldiering), craftsmen (soldiers had money, and wanted to buy things), etc. I'd imagine it was the same at every fort across the world, across most of time - they do generate wealth/prosperity, in a way. In fact towns sprung up outside most forts along the wall. Terrain was a factor though, the terrain in Britain was arable, whereas say - the great wall of china had tons of forts along it and no towns sprung up there because it was remote and most of the forts were in non-arable land. Modern armies on the other hand, simply don't allow such things to happen.