{{cite}}'''Brother''' (or '''Battle Brother''') is the lowest rank within a [[Space Marine]] [[Chapter]].

All [[Neophytes]] become Battle-Brothers after passing their initial trials and being implanted with the Chapter's [[geneseed]], before earning honour in battle and rising up through the ranks. Battle-brothers endure decades of training before becoming fully-fledged Space Marines.

The most common unit for a Brother to be assigned to is a Space Marine Squad of up to ten marines, including the [[Space Marine Sergeant|Sergeant]] or equivalent rank from whom the battle-brother takes his orders. In a typical [[Codex Chapter]], Battle-Brothers complete their training in a [[Scout Squad]], then are initially assigned to a [[Devastator Squad]] to master long-ranged weaponry, then an [[Assault Squad]] to master close-quarters combat. Only after mastering both of these aspects are they assigned to the most common formation within a [[Space Marine Company]], the [[Tactical Squad]]. If Battle-brothers show a particular aptitude for one of these styles of combat, they may remain assigned to these specialist squads.{{Fn|1}} Those which show technical aptitude may be sent to [[Mars]] to train as [[Techmarines]].{{Fn|1}}