The Senex system raid took place near the beginning of the Galactic Civil War. A Rebel pilot named Dev was on a training exercise when he unintentionally flew into an Imperial training area located within the Senex system. Thinking the Imperial starship were merely targets for practice, he destroyed them all prior to realizing his location was Imperial territory.
This conflict initially featured in the video game Star Wars: X-Wing from 1993, specifically as the initial X-wing historical mission titled "Dev's Sidestep".