What if the Thracians did try to conquer Equestria?

[Jerry246 37]

As any of you who have read the comics know, the Thracians and their tyrannical King wanted to conquer Equestria to prove that friendship is weakness. The strategy being to essentially launch a terrorist attack to destroy the friendship between both ponies and other races and then move in and commit genocide.

As in this motherfucker:

 

He legit ordered his daughter to launch a terrorist attack so he can carry out a genocidal conquest of equestria.

 

So to any that have read the comics, would Diomedes have been successful if he actually did carry out his conquest or would Equestria have wiped Thracia off of the face of Equus?