A civil war in Equestria leads to fighting, heroics, and sacrifice. What must be lost for harmony?

I was inspired by ShinePaw's fantastic work to write a piece for it. All credit for the fantastic art is ShinePaw's, and I had nothing to do with it and make no claims on it.

The fantastic piece is here: http://shinepawart.deviantart.com/art/I-ll-protect-you-206510081
though I'm sure many of you have seen it.

A sad story for a great drawing. The story was written after the coronation, which is why it has Princess Twilight and the art has the original one.