Commissioned in 2391 by Starfleet, the design was an update of the iconic profile of the Constitution class with the Excalibur being the first of a new group of state of the art cruiser line that was intended to fill a variety of roles in the fleet. They were designed with the intention of using the modular construction techniques that were favored by the Starfleet Corps of Engineers. This led to the Excalibur being able to handle almost any task with an expanded cargo capacity and advanced warp core allowing it to be tasked with solo exploration duties but also perform well as a support ship during fleet operations.
Designed and built as a new variant of the famed Constitution-class starships, the Excalibur-class honored the 400 crew members of the USS Excalibur who were killed by a disasterious M-5 wargames simulation of 2268.
In times of peace, the Excalibur class was also well suited for cargo and transportation missions with its massive holds making it invaluable to Starfleet who used these vessels extensively to resupply planets, space stations and other starships. The power generation of these ships allowed it to run industrial replicators non-stop and was often the ship of choice for missions of mercy or rapid evacuations. Furthermore, the crew of an Excalibur class ship was capable of converting the bays to temporary housing in a matter of hours allowing the ship to carry as many as 1,100 passengers in an emergency.
In terms of combat, the Excalibur class possessed a Class VIII warp core which was large enough to transfer power to damaged ships or to extend its shields to protect any ally without impacting its own defenses or systems. Engineers on the Excalibur were able to reroute that power to boost their tractor beams or allowed them to grapple enemy ships which could easily break away from lesser starships. In addition, it had enough crew to get damaged systems back online quickly and also transport repair crews to allied ships. The reinforced hull of these vessels also allowed it to stay in a fight longer, even when it faced a coordinated enemy attack.
This meant that it was designed by Starfleet to be the workhorse of the fleet, and while this was the case, others ships were able to outperform the Excalibur in some roles. This was because these ships were not able to equip the advanced sensors or laboratory modules of a science ship and lacked the heavier firepower of escorts or heavy combat starships. Despite this being the case, the Excalibur's versatility allowed it to perform well in tough situations than more specialized ships allowing it to handle situations that others were not prepared for.
Amongst the advanced technology that was standard to the Excalibur included an improved electro-plasma distribution network that was able to handle a greater amount of power and a new dilithium chamber configuration which kept the crystals stable at high warp speeds for longer periods of time. All these attributes meant that it was frequently chosen by Starfleet Captains who wanted a fast and powerful ship but one that was not designed primarily for combat. Graarvin Narl, the primary designer of the Excalibur class was noted to had said "We can send her anywhere and she can do anything. The Excalibur will carry Starfleet into the 25th century, and she'll do it with style." (ST website: Ships of the Line (website))