For a moment, it seemed like the Equine Continent will be thrown into war once more, as the expansionist policies of the newly formed Union State boil over, turning into an all-out, border-spanning military campaign. Fortunately, diplomacy saves the day, and the armies of the north are called back... Well, most of them, anyway...
As things are finally getting sorted out on the geopolitical scheme, Princess Celestia tasks the recently formed Council of Friendship (formally known as the Ponyville Council) to track down and disarm any AWOL commandos that still roaming about within the borders of Equestria. Upon hearing about their task, Discord decides to take matters into his own talons and claws...
...By summoning an arsenal of ridiculously over-powered armored fighting vehicles for all of them, and announcing an anti-aggressor free-for-all.
Mentally and emotionally stifled by the apathetic aura of international politics, a bit of excitement of, ehem, this caliber may very well be exactly what Twilight and her friends need.
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This is yet another alternative universe fic (as well as being a crossover one), and has no correlation with the "The Other Ponies: Tales from My Little Railway", or "General Winter" fics and their respective universes. All vehicles come from the Metal Slug™ series made by SNK, except for... Oh, well, you'll just have to wait and see...