from Jackill's Star Fleet Reference Manual-Ships of the Fleet Volume I - by Eric Kristiansen

Notes:
       As Star Fleet continued to expand it fleet, Command Cruiser became more and more necessary. But the basic command Cruiser design did not have the flexibility needed by field commanders to allow then to operate as a mobile base. Most command Cruisers were successful as Cruisers in them selves, and were able to coordinate large fleet movements. But the role of the command Cruiser had expanded by the early 2270’s, and new designs were needed. The Hatfield Class became the most expandable version of the Command Cruiser, giving field operations a massive boost.
        Unlike other designs, the Hatfield’s larger size and enlarge primary deck allowed the inclusion of fabrication centers, medical centers, extra repair bays, larger landing facilities, and personnel training centers. The Hatfield became the first truly mobile Starbase. The Mk I would also set a precedent for combat capability, being armed with mega-phasers, torpedoes, and powerful defense systems. Coupled with a compartmented design, the Hatfield quickly became the center for a number of small fleets, conducting both daily operations and command decisions while in the field. Like other command Cruisers, the Hatfield Mk I incorporated the dual deck bridge and dual CIC control centers, giving the ship resiliency in combat. The Hatfield Mk I still suffered from the engineering problems that plagued most tri-engine designs, and extra engineering crew were required. But the Mk I was so successful, that in early 2286, the Mk II was launched. More powerful, the Mk II extended the range of the Mk I, and increased the combat ability of the Cruiser, keeping it in the forefront of military designs.
        The Hatfield’s command abilities were severely tested on Stardate 9941.7, when the research base on Ibor Prime was stricken with radiation poisoning from it parent star. The USS Hatfield her self responded with her primary units, arriving two days after the start of the star solar activity. With communications failing, the Hatfield was forced to conduct medical procedures on the colony members, who had used up their Hyronolyn supplies, while also conducting atmospheric seeding, dozens of coordinated ground computer repairs, and search and rescue operations throughout the system. Although the Hatfield and her command group were on station for nearly a month, she proved the Cruisers abilities to work as a multi mission platform.
Star Fleet upgraded the Hatfield again in 2294, increasing the combat abilities and expanding the research base. The Mk III, still in use as a command Cruiser, incorporated the newly re-engineered FWG drive system. Although requiring greater computing power to maintain, the new FWG’s increase in stabilized power gave the Cruiser enough tactical advantage that Star Fleet went ahead with the modifications.
        The Hatfield’s were initially produced at the Bradlin City Construction Dry-dock, Troyis Construction Center and Bradilajia Dry-dock of Wall at a combined rate of 2 per year. Of the 20 built, all remain in active service. Upgrades are being performed at Troyis and Brdilajia.