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   Constitution-class starships entered into Starfleet service in the year 2245 as heavy cruisers. These ships were designed with the first duotronic-based computer systems invented by Richard Daystrom two years earlier. Over the next nine decades duotronic-based computers would be used by Starfleet and thoughout the Federation. Ships of this class were also equipped with the latest sensors, propulsion & tactical systems available and could accommodate a crew of 200 at the time. Through advances in technology and design, by the 2260's Constitution-class ships were manned by a crew of 430.

   Only twelve ships of this class had been built by 2267. Of the original twelve cruisers, the most famous is USS Enterprise, bearing the registry number NCC-1701. Between 2245 and 2270, Enterprise would be commanded by three separate officers. Under the command of James T. Kirk, the ship's third captain, Enterprise became the unofficial flagship of Starfleet and her crew became “legendary”.

   In 2270 Starfleet approved plans to radically refit all Constitution-class ships using the latest technological innovations available. This refit program began with the Enterprise in 2271; lasting 18 months and completed in 2273. Once the refit was completed Enterprise became the first ship of the newly designated “Enterprise-subclass” of the Constitution-class heavy cruisers. Despite the official designation, over time the new design would commonly be referred to as the “Constitution Refit”.

   Fortunately for the Federation and Starfleet, the completion of the refit of Enterprise allowed the ship and its crew to investigate and counter the “threat” posed by V'Ger—a probe of, initially, unknown origin but discovered to be the old Earth space probe Voyager 6. Following the successful completion of that mission, Enterprise undertook another five-year mission; the second under the command of James T. Kirk. Following this second five-year mission, Enterprise would serve as a training vessel for Starfleet Academy until her destruction in the Mutara Sector in 2285.

   With the success of the refit of Enterprise, throughout the 2270s and '80s, the other original Constitution-class heavy cruisers would receive the same refit; ending their service to Starfleet in that design. Furthermore, Starfleet would build new Constitution-class starships using the refit design; extending the service life of the Constitution-class well into the 24^th Century; as late as 2367. Amongst these new Constitution-class refit starships was the second Federation ship to bear the name Enterprise, registered as NCC-1701-A and serving Starfleet for seven years between 2286 and 2293 under the command of James T. Kirk.

Ships of the Class

NOTES

   USS Republic — For decades fans have included the Republic as part of the Constitution-class and the quasi-canonical Star Trek Encyclopedia has included this ship as part of the class since the reference work's first edition. However, this ship's class has not been officially established in canon.

   Furthermore, some non-canon sources suggest that this ship and USS Constellation were part of older starship classes and later refitted to the Constitution-class design. Possible yet, still not canon.

   USS Yorktown & USS Enterprise-A —  In an editor's note of the Star Trek Encyclopedia (2016) for the entry on the Yorktown, the following is stated:

   “(Gene) Roddenberry (creator of Star Trek) reportedly suggested that the second Starship Enterprise, NCC-1701-A, launched at the end of Star Trek IV, had previously been named the Yorktown, since it seems unlikely that Starfleet could have built an all-new ship so quickly. If this was the case, the Yorktown may have made it safely back to Earth and been repaired and renamed, or perhaps there was a newer, replacement Yorktown already under construction at the time of the probe crisis.”

   However, a non-canon, yet frequently referenced, source; Mr. Scott's Guide to the Enterprise (1987), indicates that Enterprise-A was intended to be commissioned as USS Ti-Ho with the registry number NCC-1798, however after Kirk and his crew saved Earth from the “Whale Probe” [see Star Trek IV: The Voyage Home], the ship was commissioned as Enterprise-A.

—LT, January 2026