United American Federation Marines

Outline
 * Traditional Marines in that they provide ship and installation security
 * Trained for boarding actions and defense, low/zero-G combat, and operations in orbital habitats and space stations. Not expected to make planet fall.
 * Roughly a division total. Company per capital ship. Platoon or smaller for other ships. Smallest ships have no Marine component.
 * Not an independent branch.
 * Though they do retain an independent special operations force which are considered the best of the UAF in zero-g combat.