Second founding

The Second Founding occurred after the Horus Heresy, in 021.M31. This Founding involved the division of the existing Space Marine Legions into the smaller, autonomous Chapters the Space Marines are now organised into - as decreed by the new Codex Astartes, created by the Ultramarines' Primarch, Roboute Guilliman.

The remaining loyal Legions were divided into smaller Chapters - one chapter maintained their parent Legion's original name, symbol and colors, while the remaining chapters took new names and heraldry. These original Chapters are known as the Second Founding Chapters. Each Second Founding Chapter initially shared their parent Legion's gene-seed - subsequently each chapter's gene-seed was isolated, forming new genetic lines.

Because the Marines that made up each of the Second Founding Chapters originated from one of the Legions that first served the Emperor, the chapters that were created were called Successor Chapters, a title not given to chapters created after that initial split.

It is unknown how many Successor Chapters were created - some chapters in the past ten thousand years have doubtless been since destroyed, leaving no records of their histories. Other Second Founding Chapters have been lost in more recent times and their names are all that remain of them. Some survive to this day, the proud inheritors of their Legion's histories and the traditions of their Primarch.