Son of Bretonnia
The Sons of Bretonnia, also refered to as the Lost Sons were mysterious and mystical Knights of Bretonnia. They were boys born with magical gifts, taken by The Lady at a young age. Whilst Damsels were allowed to return to their homeland, the Lost Sons stayed as her personal courtiers and servants, only riding out to war in the most dire of circumstances. Each knight was once a stolen boy of Bretonnia grown to powerful maturity and regal stature, garbed in archaic silver armour and wielding a variety of strange mystical weapons, their pale skin had a slight glow and their eyes glittered with the Lady's glory. Essentially acting as a martial counter to the lady's Damsels, the only warriors that seemed greater in Bretonnia, were the revered Grail Knights themselves.
The Lost Sons rode out beside Louen Leoncoeur upon his ascension to Grail Knight, fighting alongside him against the undead army of Myldeon. They burst from a mystical lake, riding upon bestial water-horses which snorted and grunted through dagger like teeth. Their hair rippled, swirling as if underwater and their voices roared in unison, untold years of rage waiting to be unleashed. Their charge hit home with devastating effect. The unliving puppets of Myldeon were smashed into the mud with the force of the impact, decaying bodies practically splashing apart as the silver host thundered on. Scaled warbeasts snapped and kicked and thrashed, hooked flails tore limbs from joints, tridents and spears sent bodies flying through the air. The Sons ground mercilessly through phalanx after phalanx of corpse-things with not a single loss. Only a few of their number eventually fell before the Necromancer as he invoked his foul magic. Myldeon was ultimately slain by the future King of Bretonnia, allowing the Sons of Bretonnia to return to the Lady's mystical lake.
1: Hammer and Bolter: The Court Beneath, Issue 25. by Phil Kelly