The Apocrypha of Skaros is the currently oldest-known surviving copy of the Codex Astartes written by Roboute Guilliman, the Primarch of the Ultramarines Legion, as a guide to the organization, battle order and combat tactics of the Adeptus Astartes, the Space Marines of the Imperium of Man. The Apocrypha has been frequently copied and cited religiously amongst the Imperium's Codex-compliant Space Marine Chapters. This revered tome is one of the earliest known accounts is to be found within a version of the Codex Astartes known as the Apocrypha of Skaros, and this crumbling tome claims that the Ultramarines Legion sired twenty-three Primogenitor Chapters, but famously omitted to list them all. Other sources do not necessarily agree with this number. It also lists the number of Second Found