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

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, often heading right into the next battle despite having little to no time to replace their losses.

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 explained it was still recovering from Hive Fleet Naga and lost most of its defences, but since Ward said it, most likely they just are that awesome or performed a Death Star run or something). It also seems that they took an insanely high number of casualties that they still didn't recover from in 43 years (but then again, the Iron Hands STILL haven't recovered from Istvaan V, and it's been 10 fucking thousand years), when Alaitoc showed up with Idharea's survivors at their home world. Only three hundred made it out and they were forced to become fleet based. Which 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 time, drastically slowing their growth in exchange for having significantly superior Marines. They even were attacked by a xenos species called the "cell-kin". Exactly what its name implies, with a dash of the Flood. They won. This implies that you have to be the equivalent of the Master Chief to be recruited, which would explain why recruitment is so slow. And why a Craftworld, even damaged, got its teeth kicked in by these dudes. Then they decided to go fuck Eldar with chainswords. So, they did.

17 years later they lost two full Terminator Squads 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.

One year 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 it. By the end of the millennium they were battling Iyanden and Hive Fleet Leviathan.