The name "Firefly" is legendary among the ponies of Equestria. The first Wonderbolt, she is renowned as perhaps the greatest pegasus to ever live, her speed and strength unrivaled in the air even to this day. Few know, however, that this legend of Equestria began as a frail and sickly filly from Cloudsdale.

Thousands of years ago, the greatest threat since Discord's defeat reared its head in the north. King Sombra, warlord of the Crystal Empire, allied with the Griffons to bring all Equestria under his iron hoof. His mighty armies stood ready to crush any opposition, and spies in the Equestrian military made countering this threat a massive undertaking. In an effort to stop Sombra and provide a symbol for the army to rally around, the greatest unicorns in Equestria began working on a spell to create the ultimate soldier. All they needed was a volunteer.

That volunteer, ready to give everything to defend her home against the forces of evil and tyranny, was Firefly.

This is the beginning of the legend of Captain Equestria.