This story contains mature content, you have been warned.

On March 9th of 2558, Cortana and her Guardians began their Hostile Takeover of the known universe, starting with Earth. On that same day, the Vanguard-UEG-Coalition’s Leonidas and her crew flee Earth as Cortana cripples the UNSC and Humanity’s overall force. After nine years of random jumps through slipstream space and drifting through the void, they come across Equus, an undiscovered planet in a galaxy far, far away. Gunnery Sergeant Casey Ambrose is thrust into this hostile, new world with only himself, his armour, weapons, and a squad of misfits that barely classified as ‘soldiers.’

Meanwhile, on Equus, war has broken out, and Equestria is the front line. The ponies and their allies are fighting for their lives as the Southern-Continental-Syndicate begins pushing into the Equestria’s territory, and that of her allies, eager to plunder their lands and destroy their allies. Twilight Sparkle is at the head of this war, assisting the 39th Royal Guard Regiment in the front lines; Ponyville.

Follow GySgt. Casey Ambrose and Field Commander Twilight Sparkle as they fight through the most brutal and one of the only wars Equestria has ever fought in.

Editor: None. (Please, point out any grammatical errors you find. It helps a lot.)
HiE, Alternate Universe, Halo-Esque Crossover fic.
Cover Art made by the amazing Feireee.