That sounds like a Fake Action Prologue.
btw, can anyone recommend more Literature entries for Action Prologue? I'm working on a novel draft and want to start the series with a battle scene where the main characters are described, but not mentioned by name. When the battle comes to a head and both parties appear to have fatally injured one another, the series of events is revealed be "just a fable" from decades ago, told by a random townsman.
Any recommendations for that sort of "Beginning" would be VERY appreciated!