Battle of Maxia
The Battle of Maxia was a Federation encounter with the Ferengi. At the time, the Federation had no contact with the Ferengi, so it was dismissed as the actions of a rogue alien vessel, rather than an act of war.
Sequence of Events
A Ferengi vessel attacked the USS Stargazer, which Jean-Luc Picard was serving on at the time. The Stargazer was heavily damaged but not disabled in the surprise attack. Picard utilized the tactic that would later become known as the Picard maneuver to destroy the Ferengi vessel. Although he was successful in destroying the foe, the Stargazer had lost its life support capability, and Picard ordered the ship abandoned.
Inexplicably, the Stargazer was not programmed to self-destruct to keep it from falling into enemy hands. This allowed a Ferengi Daimon -- the father of the attacker in the Battle of Maxia -- to salvage the abandoned Stargazer and later refit it for use in a vengeance plot against Picard and the USS Enterprise.