Before she became Nightmare Moon, Luna fought many adversaries who threatened Equestria. And since her return, new and old enemies have appeared with alarming frequency. But the land had peace for a thousand years while Luna was on the moon, and now the princess questions how such a thing could be possible.
Celestia offers her a completely logical and reasonable explanation.
Now with an audiobook by Illya Leonov.
Very nice! Great success!
That was amazing. It deserves a comedy tag.

Yes.
trollestia strikes again!

7798697 Thanks. I've added the comedy tag now.
Celestia you lying bitch

But I can't help but laugh
Celestia may have just made a wig-maker very rich.
Best. Prank. Ever.
I'd love to see Luna's "reply".
She just went full trollestia.
That was mean Celestia.
But funny. 
Short, sweet and unexpected ending. I love it.
When Celestia does stuff like this, it makes you realise why she wanted Discord reformed so badly. She likes a bit of mischief.
This is stupidly hilarious.
Celestia is best troll
Nice one!
E.U.P.? Am I missing something?
I've never figured the palace guards were only -- or even mainly -- personal bodyguards of the princess(es) to fend off assassins. They've got to run crowd control when the Princess is out in public (and keep her from being mobbed by adoring fans!), and they've got to secure the palace grounds so any random pony (or otherwise) can't just wander in and vandalize, loot, harass the staff and guests, etc.
that was a horrible prank, it took me forever to grow my mane back.
7799571 E.U.P. is like the military, im not sure exactly what it stands for. equestria unified protection maybe?
7799571
7799618
Actually EUP is a pretty mundane acronym - Earth, Unicorn, Pegasi. Twilight explained it in "Testing, Testing 123" while trying to teach Rainbow the history of the Wonderbolts:
Rainbow Dash: [sighs] Can't we just watch the history of the Wonderbolts movie?!

Twilight Sparkle: No! Now, just get comfortable, and experience the magic of learning. Ahem. Prior to the great Celestia/Luna rift, there was no need for the Earth, Unicorn, Pegasi, or E.U.P., Guard.
7799571 7799618 Earth (pony) Unicorn and Pegasus. The three tribes which make up the military force. It was mentioned very briefly in the episode where Rainbow had the Wonderbolts Exam.
No, lunatic was used back in the day to describe how changes in the moon supposedly made people insane.
I know you're trying to base the english language around horse princesses, but details like what was stated in this fic really irk me, even if its just for fun.
It was an enjoyable story though.
EDIT: Can we shoot for 30 dislikes?
EDIT: ALMOST (12/18/2016)
7799650 7799661 *facehooves*
You wrote it to drown out the constant background hum......
*Cackles.* Oh my god that is simply diabolical!
Trollestia strikes again!
AHAHAHAHA!!
that was delightfully evil 
Let's all take a second and consider the fact that if you try hard enough, you can hear the background hum (in some cases, it's a whistle). To be honest, when I'm trying to sleep it drives me crazy! Or am I just crazy? Please tell me I'm not the only one.
I can see the sequel now...
The Lunar Cycle
7799871
No, it is not just you. That just means you have been dabbling with dark and forbidden magics. A Friendship and Harmony agent will be by your house shortly for immediate petrification and removal to a secure location citizen.

7799677
And, in Equestria, changes in the moon were caused by Princess Luna. Therefore, anypony driven insane by changes in the moon must logically have been driven insane by Princess Luna...
7799946
What?
...Okay. It's official. Celestia is an evil genius.
7799693 welcome to the internet, where an army of faceless nerds are just waiting for the chance to jump up and offer corrections for the chance to sound smart
7799928 Things I learn, tinnitus sufferers are all dark magic users. Thats about 20% of the population, wow.
I can't believe I'm upvoting this.
7799928
What if I'm not home?
oh my god you magnificent bastard, that was glorious.
7800014
Well, they DO tend to make the sickest of heavy metal, so....
7798769 Welcome
Trollestia strikes again.
Poor Luna. Hair today, gone tomorrow...
So... it is Luna's fault?
OH MY GOD
BRILLIANT
Nightmare Moon's bald return in 3...2...1...
You know, I wonder if Luna didn't go crazy because ponies didn't appreciate the night enough, but due to Celestia's trolling. Well, here's hoping Luna comes up with an appropriate "reply" (that doesn't involve turning into Nightmare Moon again).
7799650
Strangely, I don't remember that. However. . . In one of my fics, written long long before that episode (and still sadly unfinished; I'll get back to it someday I promise!) I noted that an antique coin from the early days of Equestria had E.P.U. stamped on it. "Equestrian Ponies Unite"
Well, that was deliciously evil. Poor Luna.
Ah, trollestia at her finest.
Poor Luna. I hope she can figure out some sort of proper payback. Maybe not to react at all? I think that would drive Celestia nuts.
I wonder if Luna's hair keeps doing its thing after being cut of.
Later that night, Luna began twisting Celestia's dreams into nightmares for months. This went on for so long, Celestia couldn't get any sleep and ended up a tired mess.