Invaders

Invaders
Battle Cry	Unknown
Founding	Unknown
Successors of	Imperial Fists
Successor Chapters	none
Chapter Master	The current one's dead
Primarch	Rogal Dorn
Homeworld	Fleet-based (formerly Ogrys)
Strength	Currently 12 Marines, rebuilding
Specialty	Fighting Eldar, Not giving a fuck about casualties
Allegiance	Imperium
Colours	Light Green with gold aquila and company color trim

Not to be confused with the Invader ATV.

The Invaders are a Space Marine background chapter that has picked up notice as Matt Ward likes to add them in his codices. They have the luck of Lamenters with the grit of Crimson Fists, albeit with them often heading right into the next battle despite having little to no time to replace their losses, their suffering is almost entirely self-inflicted.

Their biggest accomplishment was destroying Craftworld Idharae. How the hell they did that, nobody knows (it would seem they simply damaged it beyond repair, later Ward explaining it was still recovering from Hive Fleet Naga and had lost most of its defences, but since Ward said it, most likely they are just that awesome or performed a Death Star run or something). It also seems that they took an insanely high number of casualties, which they still hadn't recovered from after 43 years. When Alaitoc showed up with Idharea's survivors at their homeworld, only three hundred made it out, and they were forced to become fleet-based. This may or may not be a retcon, as other information also suggests it was a combined force from several craftworlds, including Ulthwe. Of course, with no idea of their recruitment practices, but full knowledge of their absolute badassery, it could be their standards are just so high that they have very few potential recruits at any given time, drastically slowing their growth in exchange for having significantly superior Marines.

18 years later, they try to liberate a planet that Ahriman took over, only to set off a trap that Ahriman made, which resulted in the planet being ripped apart by warp fire. By the time the Grey Knights showed up to fix the mess, only 12 of the 300 marines they sent were still alive. That anyone survived tells us everything we need to know about these manliest of Marines. Maybe they should have stuck to invading instead of liberating; they seem much better at that. Wait, why were they trying to liberate a Chaos-conquered world? Everyone was probably foaming at the mouth and scratching eight-pointed stars on their eyeballs by the time the Marines arrived.

13 years after that, they somehow managed to beef up their numbers to the point that they had two full Terminator Squads. Which they then lost by trying to teleport them down to the Necron World Engine. It's not clear whether they sent both squads at the same time or the second after seeing the first failing. After the Astral Knights blew the Engine to hell, the Invaders are presumably one of the chapters that guard the Astral Knights memorial museum on Safehold.

Their homeworld was named Ogrys, which sounds suspiciously like "Ogre" or "Ogryn". Perhaps the reason for their power is that they recruited from people who are basically Catachan ("little ogryns") or something. Pretty much abhuman, or just about: huge, super-strong, and intelligent enough to warrant recruitment. Maybe now they solely recruit from their ships' crews, who would likely be natives of their homeworld. It's just an idea, but it makes sense, given how these guys have been kicking more ass than ten Chapters combined, doing shit their peers would probably not even dare attempt, let alone succeed at.

More recently, they were given Primaris reinforcements by Papa Smurf, which they promptly used to continue their anti-xenos assault, their particular hatred for Eldar allowing Craftworld Iyanden to bait them into battle against Hive Fleet Leviathan, ironically enough.