The Sons of Gideon were a former Loyalist Space Marine Chapter of unknown Founding and origin who went Renegade following mutations to their gene-seed. The Crimson Fists Chapter was called upon by the High Lords of Terra to exterminate the Sons of Gideon because they had been declared Excommunicate Traitoris after a routine examination of their gene-seed revealed that it had mutated to such an extent that the Space Marines of this Chapter had been driven insane by a chemical imbalance.
The Crimson Fists mercilessly destroyed the Sons of Gideon's homeworld of Gideon IV and then hunted down the Sons of Gideon's 3rd Company which had escaped the initial assault. The surviving Sons of Gideon had proceeded to butcher their way through the 4 billion citizens of the Solar System. Almost nothing else is known about this Chapter in the Imperial records.
The Sons of Gideon's Chapter colours are not listed in current Imperial records.
The Sons of Gideon's Chapter badge is not listed in current Imperial records.
- Deathwatch: Honour the Chapter (RPG), pg. 58