"I believe that if we are called an Empire, we must reassert our claim, yes? And the frozen north is our claim," Spike peered out the window. "Cadence, this war is what shall make or break us. If we fail, we have to win ten times, and if we win, we have win ten more times. If we want to declare, we have to declare with a army."

Shining Armour would begin to fight off the sense of guilt for fighting his sister, but would win handily. "I'm in."
Cadence would slowly peer into the distance, and will finally say "Alright, send news of declaration." Spike would blow his message to Celestia's grand palace, and on this day, the world stoppped turning.

On, April 8th of the 895 moon, The Amore Crown of The Crystal Empire declare independence from the belligerent Kingdom of Equestria, under the explicit right that all Crystal Ponies have, and for your insurrafable offences,
For Quartering large bodies of armed troops among us:

For protecting them, by a mock Trial, from punishment for any Murders which they should commit on the Inhabitants of these States:

For cutting off our Trade with all parts of the world:

For imposing Taxes on us without our Consent:

For transporting us beyond Seas to be tried for pretended offences

In every stage of these Oppressions We have Petitioned for Redress in the most humble terms: Our repeated Petitions have been answered only by repeated injury. A Princess whose character is thus marked by every act which may define a Tyrant, is unfit to be the ruler of a free people.

Under thus circumstance, it is evident that we become a free state of our peoples, Absolved from all Allegiance to the Celestian Crown, and that all political connection between them and the State of Equestria, is and ought to be totally dissolved; and that as a Free and Independent State, they have full Power to levy War, conclude Peace, contract Alliances, establish Commerce, and to do all other Acts and Things which Independent States may of right do. And for the support of this Declaration, with a firm reliance on the protection of divine Providence, we mutually pledge to each other our Lives, our Fortunes and our sacred Honor.

By endowing this proclamation to you, you are hereby given two options, to accept the Crystal Empire as a free and united state, or to hereby accept an official declaration of war.

Two days later, in Canterlot.

"I never thought that they would decide to act so rashly." The Crown Princess of Equestria stared into the paper with soured eyes, even with what her now decreased mass of subjects to divine omnipotence. It was clear moons ago that relations have soured, but never would ever consider war to be the next step. However, the Empire had in its possession far
too relics and additional items, subjects and texts of magical importance to let them fly a true flag. "I want a march into the frozen north, and spare no offence with your approach." She gained a small amount of devilish curiosity from the idea of finally annexing the Frozen North, but would things actually be this simple?

The Kingdom of Changelings

You see, This sudden march into the North cam without any warning, and the first obvious obstacle was the Changelng hive. Thorax was no Chrysalis, but he was not a pushover. Soon, A pair of gate guards would find themselves blazing and bolting to the center of the hive. "Thorax! The Equines have intruded with a army of unimaginable size! We must declare war before they do." Later that night, Griffonstone, The Buffalo Tribe and Grand Zebrasia would decide to join a fight that could have been prevented if military access was asked for. This night was a night where the had began to pump smoke into the sky again. The Treaty of Sombra's had been broken. The world had fallen into war.

Author's Note

I think this would be an important time to mention that this is all based in a sort of WW2 environment, if you couldn't tell.