Chapter Combat Doctrine
The Dark Angels follow the standard combat doctrine of the Codex Astartes, but their dogged resistance against overwhelming odds is legendary. The Dark Angels will stubbornly stand their ground in combat, refusing to give ground to the enemy, even if it is tactically beneficial to do so.
The primary driving force of the Chapter is the hunt and capture of the remaining Fallen Angels. Only by forcing every single one to repent do the Dark Angels believe they can restore their honour. If a member of the Fallen or someone who may know of the location of one, is present on the battlefield, the Dark Angels will ignore their objective and do all in their power to capture this individual. Everything else is second to the capture of a Fallen Angel, including any other human life. It is not unknown for Dark Angels to fire upon friendly targets in order to prevent them from discovering the secret of the Fallen. Those friendly units that survive are often taken to The Rock to be turned into Servitors, to silence them forever.

The Dark Angels are also notoriously intolerant of non-humans and mutants, even those like Squats, Ogryns or Ratlings who are considered benevolent by the Imperium of Man. They are also highly mistrustful of the Imperial Inquisition, and will refuse to fight alongside any force that incorporates members of the Inquisition, or non-human soldiers, except in the most dire of circumstances. This is due to the fact that they do not want the Inquisition investigating the Chapter or discovering its dark secrets.