Trekipedia

U.S.S. Excalibur NCC-26517

The Ambassador class Starship Excalibur, temporarily under the command of Commander William Riker, served as part of a tachyon detection grid during the Federation blockade against Romulan interference during the Klingon civil war of 2368.^[1] After participating in the defense of Sector 001 during the Borg Incursion of 2373,^[4] the Excalibur underwent a major refit and was placed under the command of Captain Mackenzie Calhoun and assigned to patrol Sector 221-G, formerly known as the Thallonian Empire.^[2] The ship was destroyed when the spawn of the Great Bird of the Galaxy nested inside the warp core.^[3]