Sergeant Grimm (a dude) and Corporal Tali (not a dude).

Two American soldiers and best friends (without benefits) who are in a losing fight against insectoid invaders (not a crossover, sorry... and they're not alien ants).

One being of Chaos (maybe two).

A plan that boggles even his mind, or her mind, that could end well or might end the ponyverse for a few seconds.

Follow the tale of two people, turned ponies, who have no idea how to act in modern pony society, yet have to make a living on the fringes of Equestria while carrying knowledge of human society and technology that are mostly useless in a quadrupedal world without hands, opposable digits, and a population that doesn't believe science can take them to the moon, much less that pens are more efficient than a quill.

And what's up with parchment? There are more than enough trees...

Note: Contains language American parents will fret over.