(coexisting on another dimensional plane)
A starship from the future of the prime universe was being held inside a moon of the system's gas giant. In 2155 this was discovered by Commander Jonathan Archer. After successfully staging a mutiny against Captain Forrest, Archer commandeered and forced the Terran battle cruiser ISS Enterprise to the Vintaak system in order to retrieve the captured starship, identified as the USS Defiant. Though Forrest eventually regained command of Enterprise, Archer had locked the helm controls on course for Vintaak. Forrest's attempts to change Enterprise's course ultimately proved futile.
When an away team under Archer's command beamed aboard the Defiant, Enterprise was discovered and captured in a Tholian web. In the subsequent Battle of Vintaak, some of the Enterprise's crew was able to abandon ship in escape pods, but the ship itself was destroyed with Forrest still on board. Archer captured the Defiant, damaged the drydock it was held in and took the Defiant to Earth. (ENT: "In a Mirror, Darkly")