USS Mercia
From Star Trek: Theurgy Wiki
The USS Mercia was a 24th century Federation starship operated by Starfleet.
In 2374, Rhys Williams took his cadet cruise aboard the Mercia.
The following year in 2375 and only one month into its mission, the Mercia suffered a catastrophic warp core malfunction, leading to the destruction of the ship and the loss of many lives. Ensign Rhys Williams was serving aboard the Mercia in operations at the time, and although he and several others managed to escape the destruction of the ship, he suffered a nervous breakdown and was sent back to Earth for counseling at Starfleet Academy.
(So far it has not been revealed what class of starship the USS Mercia was.)
