Introduced in 2269, the first true Constitution refit was provably more powerful (up to 3 times) more than the previous Constitution class, however with increasingly better technologies, many felt the design had reached obsolence on arrival and ordered a new block of Constitutions using technoogies from the Excelsior project. The 12 vessels converted provided service for the next 80 years in various tasks, embarrassingly their speed matched or surpassed the refit vessels making them scouts for the fleet leading to the Relop-Defrein theory which showed that exposed nacelle tips simply provided better speed leading to Starfleet abandoning the Excelsior style of nacelle for the Ambassador class. Finally the class recieved a refit post Wolf 359 to use better equipment of all kinds before being used as ECM and shield interference vessels during the Dominion war, a role they served well in despite heavy (7 out 12 destroyed) casualties leading to their post-war replacement by the Hawkeye Class