Secrets Beneath the Surface

The Secrets Beneath the Surface is a lamentable event that occurred in the history of the Argent Blades Space Marine Chapter sometime in the late 500's.M41 following the second assault on their Chapter homeworld of Alexandria. The Argent Blades looked the source of the continuing attacks on the Kolleshian Sector, which finally led them deep beneath the surface of their own Chapter homeworld. What exactly occurred is not recorded. But since that time the Chapter Command the Chapter's Purifiers have taken a vow of silence, refusing to speak on the events that occurred.

History
Following the second assault on Alexandria, the Argent Blades were deployed to suppress the remaining rebellions that plagued the Kolleshian Sector. As their kin fought on the Purifiers and Chapter Command searched for an answer to the attacks. They scoured the world, using even their serfs to instigate a thorough search of the surface of Alexandria. Finding nothing on the surface, Lord Commandant and his Angeli Puritasi descended into the depths of the Castellam Pudicitiam. Descending deeper into the numerous tunnels hidden underneath the cities of Alexandria.

When the Lord Commandant returned, the tunnels were sealed off and warded, and the command staff were gathered. Behind the closed doors of the Lord Commandant's quarters, secrets were discussed, secrets that never left those quarters. Since that meeting, the command staff all wear a black stripe on their helmets, declaring it to be a tactical designation of their rank, but the truth of the mark is known to the high command.