Twilight was conducting private studies in her basement. She was trying to create a spell that could allow cold-blooded creatures, like Spike, to survive cold weather conditions just as well as warm-blooded ponies.
Spike stood in the center of the room, nervously awaiting a test-fire from Twilight. "Uhh... Are you sure it's ready to be tested on a live subject?"
"Not to worry, Spike." Twilight assured. "I made sure to read up on a quick disabling spell before all this. So even if my spell back-fires, I'll be able to neutralize it before it causes any harm."
"Well... Okay..." Spike closes his eyes and fears for his life, despite knowing better that his friend knew better.
"3... 2... 1--" Twilight was cut off by a message being materialized between them in Spike's flame. It had Celestia's seal on it. With the letter stealing all of Twilight's attention, Spike fell on his back and sighed heavily in relief.
"Well, I guess the experiment will have to wait. We're late for breakfast anyways. C'mon, Spike. Read the letter to me as I get something for us to eat." Twilight started her way upstairs with Spike following shortly behind her with the letter in his claws.
Spike read aloud, "Dear Twilight", he was confused by the short and formal greeting that Celestia normally does not use to address Twilight, whom also started wondering what warranted it. "Ahem," Spike continued, "It pains me to inform you that my sister and I have rekindled an old fire: She has gone mad with power and we are both feuding over complete control of all of Equestria."
Twilight gasped, "No! This can't be true!"
"...I wish it weren't true, but as the situation has grown dire..." Spike paused before continuing to what he could not believe what he was about to read, "*snicker snicker*" Spike was now flabbergasted, as was Twilight. "I strongly urge you and your friends come to Canterlot immediately... Tee-hee... so that we may work together to knock some sense into-- aha ha ha ha tee hee," Spike changed to a deadpanned expression, "I can't even let my writing keep its straight face."
Twilight struggled to contain her chuckles. "Did she seriously write that?" She thought.
Spike sighed, "Okay, nothing to worry about." He rolls up the message and tosses it aside.
"Now, hold on Spike!" Twilight rushed and grabbed the letter from off the floor. She was smiling like an excited schoolgirl. "Let's not be too hasty! After all, Celestia is the one who sent this! Any message from any princess is of high priority." She opens one of the cabinets and levitates out a box of cereal. "Here. There's little enough of this for you to finish off straight from the box. You're going to eat while we gather the others."
"Ok, fine." Spike uttered in defeat. "Let's go to war." He unenthusiastically grabs a claw-full of dry cereal and shovels it in his mouth.
One hour had passed, and Twilight had already gathered all five of her friends and were all on a train to Canterlot.
Rainbow Dash was getting antsy. "I still think I should fly on ahead. Even if I hit a storm along the way, I can make it there just fine and have enough energy to fight."
"Rainbow Dash, I don't doubt that if you were flying, you'd probably be there by now." Twilight explained, "But if you did, you'd likely be outmatched: All of Luna's guards are thestrals... that can fly. Remember? She has huge dominance in the skies and Celestia needs ALL of us there together if were are going to stand a chance."
Rainbow Dash sighed and laid down on her seat. "Fine."
Applejack turned to Twilight. "Now we cahn't be the ONLY ponies she's requesting assistance from, Am ah right?"
"Well..." Twilight answered, "I'd expect the Wonderbolts to be there as well. Seeing as how they do have royal ties."
"Ah yeah!" Rainbow Dash predictably cheered. "I can't wait to kick some flank along side my heroes!" She jumps up and hovers in the air to do some shadow-boxing and ball throwing.
"It's gonna be so AWESOME!!" Rainbow Dash and everyone else was perked up at the sound of a second voice joining in on her last word. She opened up one of the over-head compartments and saw a worried Scootaloo covering her mouth. And unsurprisingly, her two friends to her side, giving disapproving stares.
"Oops..." Scootaloo whispered.
Rarity got up from her seat to stare directly at the three and scold them. "Now what in the world do you think you three are doing?!"
Rainbow Dash immediately carried on for her, "yeah! You can't be sneaking onto trains and--" She was cut off by Sweetie Belle flashing three stamped youth-rate tickets. "Okay... What exactly are you doing on a train to Canterlot?"
Scootaloo was about to speak, but Pinkie bounced up to plead their case. "Isn't it obvious? They're going to help us in the battle!"
Twilight argued back. "But Pinkie! They're too young and fragile to be in such a conflict!"
Pinkie countered. "Nonsense, Twilight!" She reaches up and brings the CMC down to the floor with the rest of them. She looks intently into their eyes while still directing her speech at Twilight. "I can tell JUST by looking at them that they are cold, brutally-scarred warriors skilled in the art of frozen warfare who would be PERFECT to have at our side in battle!"
"Uhh yeah!" Applebloom agreed. "What she said!"
"Umm..." A timid voice started to speak up from behind Pinkie. "I'd prefer if we just called it a snowball figh--"
"Boulderdash!" Pinkie pounced Fluttershy. "How can you say something like that about something so serious?! Anything that involves the princesses is certainly no laughing matter! Do you see me laughing?!" She pokes Fluttershy in the chest.
"B-but it is--".
"No excuses!" She jumps back to the center of the train car and addresses everyone. "We need to be ready the moment we get off this train! Any wrong move could slow us down. And until then, I say we get ourselves prepared; create battle plans and warm up!" She finishes her speech by donning a drill sergeant's hat. "At ease!"
Twilight began talking back. "Pinkie. Don't you think I should be in charge since--"
"Don't be back-sassing me, private!" Pinkie rushes to Twilight up close. "You know I know more about this situation than you do! Do you want to be responsible when everypony in this room comes down with a bad case of the sniffles?! I didn't think so! Now WHO is the Alpha?!"
Twilight sighs, "you..."
"Speak up, scumbag!"
For the sake of ending her silly charade, Twilight played along. "Sir, you are the alpha, sir!"
Pinkie backs off. "As for the rest of you, practice your war faces and PT until we depart!" She marches to the back of the train car.
Everyone else decided to do push-ups and whatnot whilst stretching their facial muscles.
Later into the afternoon, Celestia has sent her guards back into the field, but ordered them not to make any attempts to advance. After Luna's kamikaze, Celestia needed to be set for anything else her sister may try. Blast that Luna! She's too crafty for her own good. She still had not gotten over her "near-death" experience.
One of her guards meets her back in the throne room. "Your highness! We have just caught glimpse of Twilight's train arriving at the station. They should be here within 15 minutes."
"Thank you."
"Have you heard back from your other drafts?"
"The Wonderbolts have replied back saying that they will be able to fight once they mobilize their other members from different regions of Equestria. They plan to swoop in all at once to bombard the opposition the moment they arrive."
"Do they know which side to attack, Princess?"
"Yes. Now I am not sure about the condition of all my other drafts, I have not heard back from them. Hopefully they will be here soon." Celestia rests back in her throne and continues drawing up battle plans as her guard exits the room.