Following decades of service, the Federation ultimately decided to perform a mass upgrade of their Constitution fleet. The
installation of new technologies and a nearly complete rebuild left such ships as the U.S.S. Enterprise and U.S.S. Yorktown completely
refurbished and ready for several more decades of service. The age of these ships, however, had passed and it did not take long for them to
be either destroyed or phased entirely out of service, the Excelsior Heavy Cruiser surpassing the refitted Constitution class vessels.