Excalibur (free starship)

In the mirror universe, the free starship Excalibur was Galactic Commonwealth Valdore class warbird in Starfleet service in the late 2370s. The ship had been built by the Romulan Star Empire and commissioned as IRW Valdore. Following the loss of its crew at the Battle of Bajor, the Valdore was recovered by Memory Omega and renamed Excalibur by Mac Calhoun, who became its new captain.

Construction
In late 2378, the IRW Valdore participated in the decisive Battle of Bajor against the Klingon Empire and the Obsidian Order. During the battle, the Valdore was heavily damaged and lost its entire crew. A microsecond before the Terran Rebellion Excalibur rammed a Klingon bird-of-prey to prevent it from launching a trilithium warhead at B'hava'el, the Excalibur's consciousness, Mark McHenry, transferred its crew onto the free starship Enterprise and itself into the derelict Valdore.

Memory Omega recovered the hulk from the battlefield and transferred it to Erebus Station for repairs. When Director Saavik led Captain Calhoun and Soleta around the station to choose a new vessel, McHenry contacted Calhoun telepathically and reported the cloaking device was still in working order. Calhoun asked Saavik for the Valdore and had it renamed Excalibur.