Opening Narration: Majors!
When aliens came, they didn't come from Tartarus like we had been expecting nor did they come from the farthest reaches of the land, where no pony had ever explored. They came from beneath the sea; a portal beneath dimensions, in the Equestria Ocean.
Something out there had discovered us.
The first Major made landing in San Prancsisco, the second hit Maneila, and the third, Capony. That was when we knew, sure as sure, that this was not going to stop. We managed to kill the first few with conventional weapons, but it took a week, many ponies died in the meantime, and it was clear that we could never win that way. It was clear to them, too. They expected us to fall easily, crunched under their house-sized feet.
Surprise.
We didn't. The boat that had discovered the rift had also seen a book come through it. We didn't know where it came from, or how it survived the trip, but when we read it, it turned out that it was written by a race that had already survived attack by the Majors. It left details on what the Majors were, but most importantly, it showed us how to stop them. The Forerunners, as they were called, had decided that they couldn't defeat the Majors small, so they went big. To fight monsters, they made their own monsters out of metal, and called them Jaegers. The book contained plans on how to make them. There were many technical aspects that we didn't understand, but a fashion designer from the small town of Ponyville solved that.
Rarity, as she was called, made a name for herself as a heroine when she figured out how to use magic with gemstones to imbue these Jaegers with to allow them to work off our magic. She also adapted their forms to suit ponies, making them in the forms of Alicorns. These were called PON-Jaegers. It was soon shown that they couldn't be used without three pilots, one of each type.
Though not by Rarity, that problem was eventually fixed; the Forerunners had described a “neural bridge” that they used to connect their pilots' minds and synchronize them. This, too, was adapted for magic. Later PON-Jaegers were armed by another resident of Ponyville, one Pinkie Pie. A weapons genius, but still nobody understands her wish to include a “party cannon” in each PON-Jaeger.
And with these PON-Jaegers, we fought back. We started winning, and then everything changed. They had counted on us ponies to fall as easily as our small stature suggests. I've heard that we don't look in any way too dangerous. They had never expected us to rise up to meet their challenge. Sure, the Forerunners helped, but we are ponykind. We have survived, and with the elements of Harmony, defeated such threats as Nightmare Moon and Discord. We have colonized the edge of the Everfree, and we have stood our ground against all comers. We are ponykind, and we never submit to those who would do us harm. We stood proud against the Majors. But pride goes before the fall, and we fell hard.