This is not the anniversary of a war. There was no war. Shell Shock is not a veteran, and he does not have nightmares. And even if he did, he wouldn't be able to tell anyone.
There was a time when ponies were not quite so friendly. A time when such qualities had to be tested by the introduction of unknown elements. In a world before Equestria, the unknown element called Princess Twilight Sparkle is introduced.
When the Queen of the Changelings decides to punish an uprising, she makes the mistake of giving the outcast a chance to speak before going on the chopping block.
While browsing the Star Swirl the Bearded wing, Twilight Sparkle learns something tragic about the history of Equestria and the meaning of her cutie mark.