|Battle Cry||"For Ithaka!"|
|Successors of||Ultramarines (officially)|
|Primarch||Roboute Guilliman (officially, implied to actually be Alpharius)|
|Specialty||Infantry, close combat|
|Colours||Gunmetal armour, White Pauldrons with red trim, Blue Iconography|
The Iron Snakes is a Chapter of Ultramarines descent. Their primary mission is to guard the Reef Stars from mostly Dark Eldar and Orks. They are based on the Ocean- and Feral World of Ithaka. Their heraldry kind of looks like the Grey Knights, except less pimp and anti-Daemon stuff. They also seem to be a relatively popular Chapter on the tabletop, probably because of their uncomplicated but still good-looking colour scheme.
There also seems to be some greek inspiration to their theme, as Ithaka, which their home planet is called, was the home of Odysseus in the Odyssey. Combined with the bone-white pauldrons and having a "Damocles Squad", it's fair to say that these guys are about as ancient Greek as the Minotaurs.
The Iron Snakes were created during the Second Founding. They have been stationed in the Reef Stars for thousands of years. While most of the sector is relatively low-tech, the Chapter is very serious about this duty and will go to great lengths to defend the population against any threat, primarily Dark Eldar and less frequently Orks.
The Chapter has fought in several major crusades, including the Sabbat Worlds Crusade, where they only lost eight marines against almost thirty thousand Chaos casualties in a battle, and the Thirteenth Black Crusade.
The Iron Snakes restrict their forces to the one thousand Astartes the Codex Astartes dictates, but they ignore the company structuring, instead basing their organization into a hundred ten-man squads that function somewhat autonomously. This means that the squads contain battle-brothers of all levels of expertise, pairing veterans with novices. If a squad is wiped out to the last man, that squad will be reformed under the same name and with new Astartes from other squads. Each squad also has its own standard-bearer, as well as an special weapons bearer, and apparently all squads also have their own Apothecary, leading to the Chapter having a much higher number of Apothecaries than usual. On the tabletop, they are probably best represented with Red Scorpions chapter tactics, as they have a similar apothecary fetish.
Despite the loose organization, they still have a hierarchy which includes captains. Dreadnoughts and the recruiting and training of neophytes are left to the command staff, though squads are usually assigned to help out training once in a while. Neophytes are combat trained and turned into Astartes right on Ithaka, those who complete the transformation are given their power armor and become full Astartes, so no Scouts and no neophytes in the field.
Though they're as much about teamwork and brotherhood as any Astartes, Iron Snakes also place a value on their troops being able to act alone if necessary, as they recognize any supersoldier worth his power armour should be able to kick some ass on his own. Given this, Iron Snakes will sometimes deploy a new Astartes to solve minor issues to see if he can act reliably independently, or veterans to conduct harassing maneuvers on enemies.
It seems their Chapter Master inherits the name of the previous one (or there are only like, 4 names on Ithaka), as their current Chapter Master is the eighteenth to bear the name Seydon. The current Seydon is an ancient and seasoned Astartes, pretty friendly too. He always wears a hood, so we don't get to see his face beyond the beard and jawline. He's also fucking hueg, noted for being a meter taller than a line Astartes.
For some reason, possibly because everyone in the Reef is so low tech, the Iron Snakes seem to fight with less sophistication than most chapters. The Iron Snakes see fit to fight using ancient Greek phalanx tactics, complete with spear and shield line formations with assistants behind them to carry a half dozen spears and reload the Boltguns. Even more puzzling is that they seem to use these tactics without any real armor support when fighting an Ork Waaagh of all things. Never the less, Iron Snakes do have war machines and do use them from time to time, while they still have a large enough fleet to have an effective presence across the sector, so who can say why they use such primitive tactis.
The Iron Snakes are listed as an Ultramarines successor in the Codex: Space Marines (7th Ed). Dark Imperium by Guy Haley confirms that the Iron Snakes are a Second Founding successor chapter of the Ultramarines. In the novel, Know No Fear, the Ultramarines 6th company led by Captain Saur Damocles wears the emblem of a snake similar to the heraldry of the Iron Snakes. One of the founding squads in the Iron Snakes were also named Damocles Squad. As such, it is possible that Damocles was the first Chapter Master of the Iron Snakes, but this is yet to be confirmed.
That said, the XIII was the Orphanage for Lost and Troubled Space Marines during the heresy, what with their adoption of warriors from the Lost legions and the Iron Warriors. That's lead some to suspect that the Iron Snakes are Alpha legion loyalist remnants, what with their focus on army compartmentalization and versatility, common deployment individual astartes to serve as operatives and sabotage behind enemy lines, the serpent in their heraldry, and that their chapter master is a larger than the average astartes, conceals his face, and has been known to swap identities.
This picture is cool and all, but it's impossible to unsee the Angry Marine in disguise in the background.