The first five books are set on the planet Bellevue, previously part of a high-technology galactic civilization (the Federation). Interstellar civilization collapsed during "The Fall", when extensive civil war greatly reduced the planet's technology level. Technology has redeveloped only slowly: the most advanced groups have reached the level of double-expansion steam engines, wrapped-brass-cartridges breech-loading rifles (Martini-Henry lock or very similar) and lever-action carbines, cast-steel breech-loading cannon, simple revolvers, etc. Progress is slow: the breech-loading rifle design has not changed for over two hundred years, and other groups still use flintlock or percussion cap weapons.