Commander Hurricane was a pegasus military leader from Equestria. She was the leader of the party sent by Princess Celestia to drive away Stratopolis from the borders of the land. Rainbow Dash feels a deep connection with her since they both have/had a rainbow mane.
She left a holographic warning message to stay out of the center of Stratopolis, but the Lounge leader Razzar ignored it and unleashed the Smooze. Rainbow eventually uses the Sword of Solstice found in her tomb to fight back the Smooze.
Due to the twisting of history over centuries, and her body's ability to react to the machine world (even after her death), she became known as "The Valkyrie" and an object of worship to the inhabitants of Durandana.