Thanks to some unforeseeable quirk of warpspace, the Unquestionable Perfection, the Scions of the Konic's shoddy, barely-functional jalopy of a Gloriana-class Flagship has made planetfall on a planet that has just emerged from the warp, a planet orbited by a moon and a miniature sun and inhabited by a bunch of cutesy, colorful, weirdly horse-like xenos. 

Fortunately, Captain Severa, Master of the Keep and the Scion's acting Chapter Master, has decided that the Chapter of Space Marines has better things to be doing than wasting ammunition and weaponry on this planet's oddly horse-like xeno population that would be better spent on actual threats, and sends the rest of the fleet ahead to their intended destination while the 1st Company and whoever else happened to be on the Perfection when it crashed stay behind to get it back up into the air, hopefully before the natives notice the supersized battleship that's now sitting smack-dab in the middle of what they call the Everfree Forest and start poking around it. 

Unfortunately, a wrench has just been thrown into the works of Captain Severa's plan. Two wrenches, actually, in the form of a Heretic Astartes legion that shows up a few days after the fleet leaves and starts pillaging and burning their way through the local xeno population, and the Chief Apothecary's decision to take pity on a certain injured lavender alicorn. 

And thus begins the story of how the second most looked-down-upon chapter of Space Marines in the entire Imperium of Man(the first being the Lamenters, of course) ended up forming a semi-permanent alliance with a bunch of ridiculously adorable technicolor ponies, and in doing so added yet another item to the very long list of reasons why the Ecclesiarchy hates their guts.

While this is a Warhammer 40k crossover, I have endeavored to write it so that minimal knowledge of Warhammer 40k is required for people to understand what is happening in the fic.

Credit to GrayStonePony for the cover art. While it isn't specifically related to Warhammer 40k, I think it captures the tone of the fic pretty well.

If you have questions, concerns, or constructive criticism, please leave a comment. On a related note, if you're going to downvote this, a comment explaining the reasons why you did so would be appreciated.