The Marble Faction is a political party within Steelhold. Following its loss of control under Corley and Asmoth's reign, the Faction went underground and operated in secret. It's current status is unknown; many manifestos were sent from Steelhold with the hopes of spreading the Faction, but after Steelhold's fall none of the original organization survive.
The Revolutionary Monument commemorates the 258 Revolution, in which the Faction seized control of Steelhold. It only managed to maintain its power for a single year, and was crippled when Emdief withdrew from politics and handed the reigns of poewr over to Corley.
The Marble Faction is in favour of Steelhold's independence, instating equal rights for all dwarves, and balancing the power of the Overseer position against a council of fortress notables. Since Emdief's passing, the organization has begun espousing the socialist ideals of Jovus, namely that the state should provide all of its citizens needs and almost all property should be controlled by the state - although, that basically already happens in Steelhold. The Faction is rather Utilitarian by nature.
The faction is strongly opposed to magic and magic users on the grounds that magic is beyond dwarven control. It used to be opposed to vampirism, but now basically all of the surviving old guard are vampires. Go figure.
The remaining loyal members of the Steelhold Council are Jovus and Uristador. The hierarchy within the faction has really broken down, and power is currently shared between them.
The Faction at one point had its own military, which it called the Revolutionary Guard. The Guard consisted of 1.5 squads of Marksdwarfs led by Emdief (these consisting mainly of former military engineers under Rhaken) and later a full squad of Lashers armed with looted goblin whips. After Emdief withdrew from politics, many of the Guard were drafted as members of Corley's baronial army.
Uristador's position as militia commander and active recruitment within the militia means the Guard unofficially returned during Asmoth's reign as an incredibly disorganized mix of soldiers and archers. The Guard eventually expanded considerably with all surviving vampires being drafted into its ranks. This remnant of the Guard ceased to function and disbanded during the Fall of Steelhold.