By the time of the American Civil War (1861-1865), it was already recognized that rifled weapons were the future of the battlefield in the accuracy-at-range that the weapon types provided. This led to a period of modernization for both small arms and artillery systems. Militia general and engineer/inventor Charles T. James looked to perfect a process in which the readily-available bronze smoothbore field guns could be converted to more effective rifled forms in the numbers required for the Union war effort. This eventually led to the generic term of "James Rifle" being applied to a series of guns featuring his rifle pattern and most were of 14-pounder form.
The need for rifling was apparent in the early part of the war when smoothbore guns still reigned supreme for both sides. However, these bronze creations saw inaccuracy creep in through the loss of material or deformation of it during action. Charles James partnered with the Ames Mfg Co. of Massachusetts to further his pattern along and this led to a new rifled cannon with a bore exceeding 3" being born - the 14-pounder James Rifle mentioned previously. Stocks of 6-pounder Model 1841 bronze smoothbore guns (detailed elsewhere on this site) also followed suit.
The base design was consistent with artillery pieces of the period. The gun tube, tapered at its business end, was seated atop the mounting hardware which included a single tow arm. The carried involved a pair of heavily-spoked road wheels and the crew was positioned all around the weapon when it was operated. As with other muzzle-loading artillery pieces of the period, the weapon required multiple crew members for optimal efficiency. Siege-minded versions of guns were mounted on appropriate siege carriages for stationary, defensive fire.
In the end, the process of rifling existing bronze artillery pieces was not an outright success. While bronze proved an excellent metal for artillery for its part in history, it proved too soft for extended use in the rifling process - leading to the rifling grooves wearing out prematurely. As such, the James Rifle process, and its corresponding James projectiles developed for it, were succeeded by more modern, practical artillery solutions before the end of 1862 (James himself died in late-1862). Some siege guns using the James Rifle process were fielded in the bombardment of Fort Pulaski in April of 1862. Additionally, some Federal naval guns were rifled with the James pattern out of necessity.