[7] On his forty-seventh birthday, Cameron has been quoted as having said he had been a cow-boy, a plough-boy, a collier, a blacksmith, a tanner, a tailor, a printer, a brewer, a contractor, an alderman, a superintendent of railroads, a lawyer, a prosecuting attorney, and an aide to the governor.

[9] By the time the Civil War began, Cameron was in retirement at an estate on the banks of the Susquehanna River according to some sources[10][11] while at least one reference states he was superintendent of the Northern Central Railway at Sunbury, Pennsylvania.

[9][12][13] At the outset of the Civil War, James Cameron decided to serve as a matter of duty and he proceeded to Washington, D.C.[1] The 79th New York Volunteer Infantry Regiment, known as the "Highlanders" because its initial core militia companies were composed mostly of Scotsmen or men of Scottish descent, was one of the earlier units to arrive in Washington, D.C., after President Lincoln called for troops to suppress the rebellion.

[18] On July 7, 1861, the 79th New York Infantry moved to Virginia as Major General Irvin McDowell began the advance of the Union Army that would lead to the First Battle of Bull Run.

[19] One account of the 79th New York Infantry going into battle on Henry House Hill, where Confederate forces had started to rally, at a critical point in the First Battle of Bull Run states that Colonel Cameron was on the right side of the regiment's line and shouted "Come on, my brave Highlanders" as the line advanced.

"[22] A private in the 79th New York Infantry, William Todd, wrote that as the regiment was half way up the hill, they were hit by a volley from the Confederates that staggered them.

"[23][24] Cameron continued to inspire his men with his bravery in leading charges in an effort to recover Union batteries lost on Henry House Hill.

[9] Reforming at the direction of their officers after having been first repulsed, the regiment proceeded only to be hit by another volley that killed Colonel Cameron and inflicted additional casualties.

[20] Confederate Colonel Wade Hampton sustained slight head and ankle wounds during the charge of the 79th New York Infantry[21] and while lying near the Henry House, tried to direct his men through messages carried by staff officers.

and the Confederate authorities replied back that the retrieval of Cameron's body was not a matter that concerned them, and they would not accept unless the letter was properly addressed.

He testified that Cameron's body had lain unburied in the hot summer weather for a few days prior to being placed in a common grave with other Union dead, and that he had made a mental note of where it was buried after hearing that a reward was being offered for its recovery.

Cameron's personal effects and $80 in cash he had been carrying were missing; the slave said that Confederate cavalrymen had looted of the body of anything valuable.