Based of PISOT II over on Alternatehistory.com

Princess Celestia only wants to fulfil your values through friendship and Ponies. Never mind that you're a Pony who's only in this mess because you happened to be in the wrong place at the wrong time because of the wrong career, and it doesn't matter if the Equestria she created for you bears only superficial resemblance to your memories; it's been nearly ten years since you last set foot on Equestrian soil, and it was a sub-optimal version of Equestria anyway...

Two brothers: an Earth Pony, and a Unicorn, travel across the Irish countryside in the spring of 1923.

A Conversion Bureau story taking place in an alternate history. Contains some political themes, especially near the end.

Captain Valentin Sokolov and his men run into some trouble involving Celest-AI.