Trumpets blared as Ponies gathered around Canterlot castle for what was said to a be a "special announcement" from the Princesses. There was a massive commotion among the populace about what was going on, ranging from "new coronation" to "Changeling invasion." Eventually the Princesses had finally appeared on the balcony.
Celestia spoke first, "Ponies of Equestria, today is a day we never thought would come, today we declare war!-"The Ponies were shocked by this, "-On whom you may ask? It is simple, the Humans!"-She created an image of a Human with her magic.- "These abominations have destroyed their planet, killed each other for no reason other than greed, and have enslaved the wildlife of their world! Today we march and stop them!" She shouted from the balcony.
Luna spoke next, "We shall free their planet from the grip of darkness and give them a brand new start as Ponies using a new serum we hath created! Please sign up for the Equestrian army at the nearest recruiting station today so thou can buck up Humanity as well!"
It was now Cadence's turn, "We shall spread love to Earth and the Human species, but only with your help, please join the Equestrian army to save the Humans!"
Celestia suddenly pushed Cadence out of the way, "Also I will be changing my name to Xenolestia."
~Off the coast of New York City two days later~
"Alright soldiers, your mission is simple: convert as many Humans into ponies as possible with these conversion bows." Shining Armor pointed a hoof to a crossbow with it's darts covered in a strange liquid while addressing his minions Soldiers as they sailed to NYC via boat. "Once we get to the shoreline focus on targeting the Human armies that will inevitably try to escape freedom!" He shouted. The air was filled with a cry of "Yes, sir!" And the boats eventually reached the coast.
The Equestrian forces quickly disembarked and started shooting wildly and Human civilians, many of which were turned into colorful horses.
~Random military base near New York~
A random idiot ran straight into the base shouting "PONIES ARE ATTACKING!!!!!!!!!1" until he crashed out through a wall.
The commander quickly turned to his men, "Get ready to launch a counter offensive and fuck shit up."
The soldiers quickly prepared for a battle against cuteness. Among them was Lieutenant Gary Stu, a famous man who drove a tank so well, he won five Nobel peace prizes. There is no reason to explain what he looks like so let 's just move on now.
~New York City~
New York was in absolute chaos, Ponies were running rampant and turned thousands of Humans into adorable Ponies. The US army overlooked the sight with disgust. "Alright then, send in the Helis!" Shouted the General.
Suddenly Helicopters flew over the City and started firing all over the place, inflicting severe casualties on the invading Ponies. "Alright, CHARGE!!!" The General shouted.
The soldiers quickly ran into the Metropolis and immediately pushed back against the Ponies. Gary Stu was the greatest of all, he dropped thousands of Ponies like flies as the Humans advanced on the enemy lines.
~Meanwhile from the Ponies' POV~
A seemingly imminent victory quickly turned into a disaster as those monstrous Humans killed thousand of innocent Ponies with no remorse. Shining Armor saw this with fear and order his troops to move back. He noticed a lone Human firing all over the place, he took aim at him, and fired.
The arrow simply bounced off of Gary due to his awesomeness and he turned to face his assailant. "Sup bitch?" He asked before quickly grabbing his gun and shooting Shiny. A voice in the air shouted "HEAD SHOT!" As he fell to the ground. All of the remaining Ponies started fleeing back to their boat, but they were all slaughtered by Gary's badassary.
~Later~
Gary had been given a Medal of Honor for his valiant fight for his species, now the United Nations was planning a massive invasion of Equestria. Nations put aside their differences to fight against this alien threat. Even though Vatican City would be able to defeat them on their own.
~Canterlot, Equestria~
"YOU BUCKED US ALL!!!" Rainbow Dash shouted at Princess Xenolestia.
"Now now Rainbow Dash, it was only a minor set back. We will gain the upper hoof soon. Do you disagree?" Xeno replied.
"Well I-um..." Rainbow stuttered.
"If you disagree I will kill you!" Celestia shouted.
"But Shiny is dead now!!!" Twilight Sparkle shouted before looking at Cadence. "Don't you care for him?"
Cadence gave her a blank stare, "I didn't really like him anyway." Twilight was enraged by this and punched her sister in the face, because that's fine in Equestria.
"Calm down now. You six must use the Elements of Harmony against the Humans if they reach Canterlot, that should stop them from taken over and destroying Ponykind. If you say otherwise you will be executed." Xenolestia ordered.
Later in Fillydelphia
The Humans were coming, they were landing on the shore, they were killing everything colorful. And Gary Stu was doing most of the effort as usual. Every single building was being destroyed by explosions, and the Humans quickly overtook the City.
Suddenly, Gary started glowing, and then he was flying because fuck logic! He quickly flew with his group to seize a small town called Ponyville.
The attack was brutal, hardly any of the town remained after the Humans launched their assault. Everything was now on fire, hundreds of Ponies dead, and many more imprisoned. Also Angel bunny was among the casualties.
Now it was time to invade Canterlot, the capital and heart of Equestria. Everything was ready, every man was prepared, now was the time to end the war.
The attack was going smoothly, the Ponies were too afraid to fight back, and now they had reached Canterlot Castle. Suddenly they were faced by six mares wearing necklaces, they started to glow, but then Gary Stu flew in from behind shouting "SURPRISE MOTHERFUCKERS!!!" Before shooting the Purple one in the head.
The necklaces stopped glowing and the Other five mares were killed, now the Humans were in the castle. They barged into the throne room, lead by Gary Stu. He quickly shot Cadence before turning to the other two Royals, Xenolestia was hiding behind her sister, a true act of cowardice! Gary quickly ended their suffering and the Humans there cheered for him and celebrated. Today was a great day for Humanity. Suddenly they spotted a nuke, words on it read "From North Korea" it exploded and everyone but Gary died because he is awesome.
Gary was congratulated for his victory and was known across Earth, many told his tale for years. Eventually he would grow up to be president or the Multiverse.