Nation-in-Arms is the sixth File:Military.png Military Research available at the Library. It is preceeded by Levee en Masse and leads to Selective Service. Nation-in-Arms unlocks the Bunker, the Redoubt and the third and final level of Fort technologies. The default cost is 1300 File:Knowledge.jpg Knowledge and 500 File:Metal.jpg Metal, the default research time 38.3 seconds (575 frames).