Fists Exemplar

Fists Exemplar
Founding	Second Founding
Successors of	Imperial Fists
Successor Chapters	likely every Chapter from the 3rd Founding onward who thinks they are actually Imperial Fist successors.
Primarch	Rogal Dorn
Homeworld	Originally fleet based, then Eidolica, now the Phalanx
Strength	Officially zero, secretly a full 1000
Specialty	Embracing the codex more warmly than their brother chapters.
Allegiance	Imperium
Colours	The original Fists Exemplar left their armour unpainted (like the Grey Knights).

"Sometimes, you have to destroy something old to make something new. The Fists Exemplar know that better than any of Dorn's sons."

– Marshall Behemond of the Black Templars

The Fists Exemplar were a Second Founding chapter of the Imperial Fists Legion, made up of those brothers who most closely embraced Guilliman's Codex Astartes.

History fails to mention them after M32 however, and by the time of 40k they are utterly unheard of, not even counting amongst the Second Founding successors of Imperial Fists, for they became the Imperial Fists at the end stages (read: when good'old Slaughter Koorland died Manly). A company of them also defected to the Iron Warriors, leading Chapter Master Thane to wipe all knowledge of their existence, being the very first ever Chapter created after the First Founding to fall to Chaos.

History

When Rogal Dorn teetered on the brink of a second civil war with his own brother over the need to break up his Legion, not all Imperial Fists agreed with him. One Captain: Oriax Dantalion spoke out in favour of the new codex, which unfortunately brought him the enmity of his own Primarch.

Thankfully, when Dorn finally came to realize that it wasn't worth fighting over, he rewarded Dantalion with a chapter of his own, who would be the "Exemplars of the new Order", while the zealous crusading types went with Sigismund to form the Black Templars, the youngest and most liberal (by Astartes standards and grimdark) went with Alexis Pollux to form the Crimson Fists, the most attrition specialists who fought on the walls of Terra became Excoriators while Dorn kept his closest few for himself in the Imperial Fists.

The Fists Exemplar were given a star fort: the Alcazar Astra and were tasked with patrolling a mini Eye-of-Terror called the Rubicante Flux and kept the region safe from traitor space marines and pirates who popped out every now and then.

That was until a warp flare up caught the star fort and forced it to land on the planet Eidolica, where it beached and became a land bound fortress monastery because no-one in the Mechanicum knew how to fix those types of engines.

544.M32 War of the Beast

See here.

The next Imperial Fists

As noted, there is little to no mention of the Fists Exemplar in the fluff outside of the Beast Arises series, which took place on 544.M32.

During this war, the Imperial Fists chapter itself was reduced to a man following the initial Ork invasion of Ardamantua, leaving the Phalanx near abandoned and the Chapter practically extinct.

However, the Imperial Fists are noted to have been involved in The Beheading in 546.M32, meaning they somehow made a miraculous recovery. Which is not feasible given the short space of time with which to culture new gene-seed and train marines.

Not only that, but captain Maximus Thane has purportedly inscribed his name on Dorn's skeletal hand; an honour usually reserved for Imperial Fist chapter masters.

That, coupled with the Fists Exemplars lack of recognition elsewhere seems to suggest that the Exemplars neatly replaced their parent Chapter in history, as the Imperium would likely not publicly allow a First Founding chapter and the protectors of Terra to fall in such ignominy.

Confirmed in Shadow of Ullanor, the Fists Exemplar formed the core of a "reborn" Imperial Fists chapter made up of the greatest Marines from all the successor chapters. When the remaining members of the old Fists Exemplar defected to join the Iron Warriors, Thane had all records of his former Chapter destroyed - thus explaining their absence in the list of known Second Founding Chapters. Strange how they would tolerate them joining ranks however, the Iron Warriors would sooner exterminate themselves than allow pure Imperial Fists to join them. They barely tolerate the Warsmith Honsou for having both Iron Warrior and Imperial Fist gene-seed and even then they hate him for existing. Most likely the author realized the Fists Exemplar had been dropped out of the Codexes (perhaps forgotten about or just disliked by Geedubs for being an odd one out among their Legion) and decided to make a reason for it for whatever reason. Or in universe it could be explained by that that particular Iron Warriors commander was so low on troops at that time that they had no choice but to except them in as they were desperate for manpower. Alternatively, the gene-seed racism may not have been as bad several thousand years before Honsou's time.

(Perturabo might have smirked at the fact that Dorn's Sons have defected to his Legion)