Closely related in design to the Galaxy-Class, the Nebula-Class vessels came into service in the second half of the 24th century. Major changes in design were implimented by the year 2374, making the ship's hull and deflector dish more Galaxy-Class styled. Several of the refitted Nebula-Classes had part in the assault to stop the Dominion and the Breen from driving the Federation Alliance out of the Chin'toka system.