Heenan died at Green River Station, Wyoming Territory in October 1873, and is buried at St Agnes Cemetery, Albany, New York.

[4] The family had emigrated from Templemore, County Tipperary, Ireland shortly before, and after receiving an elementary education, the boy began work at Watervliet Arsenal, where his father, Timothy Heenan was also employed.

There is no detailed record of what he did there, but the New York Clipper reports he was a local celebrity as a powerful boxer, and had proved uniformly successful in fights in private bar rooms.

Six feet two inches tall, and weighing around 190 pounds, his strength and endurance became legendary, and his success in many casual brawls earned him the nickname Benicia Boy.

[6] The prize ring was in fact outlawed, but on December 10, 1857, Heenan fought a legal exhibition bout against Joe Coburn at the National Hall, Canal Street.

[7] He made a living as a "shoulder hitter" – a strong-arm man who might be hired for enforcement or protection in the seamy and often violent worlds of New York business and politics.

As well as there being a personal rivalry between the combatants, there was a social and political dimension to the fight[6] as the nativist faction in the city tended to favour Heenan.

As Harper's Weekly put it, "the bulk of the people in England and America are heart and soul engrossed in a fight compared to which a Spanish bull-bait is but a mild and diverting pastime.

"[13] On the other side of the Atlantic, The Manchester Guardian observed that "no pugilistic contest ever decided has excited so great an interest, both in this and other countries, as the forthcoming conflict between Sayers and Heenan.

"[14] Heenan's training (unlike that of Sayers) was frequently disrupted by the interventions of police and magistrates, but by the day of battle he was in prime condition, and confident of victory over an opponent eight years older, forty pounds lighter and five inches shorter.

The referee had little option but to declare a draw, but the American Heenan complained bitterly that police had colluded with Sayers's supporters in breaking up the fight as soon as it became clear that the Englishman was beaten.

Heenan loudly demanded a rematch, but Sayers's damaged arm made this impossible, and the two men were finally reconciled, each being awarded a championship belt.

[16] A large crowd of "sporting men" thronged the London station from which Heenan departed on his way to Southampton to catch the steamer to America.

Heenan did not remain long in the U.S. Just a year after the battle at Farnborough, the country was torn apart by civil war, and the Benicia Boy returned to England in March 1862.

[20] The result was controversial: many American observers later agreed that King had been given longer than the rules allowed to recover from a knock-down in the eighteenth round,[citation needed] and Heenan claimed some time after the fight that his subsequent collapse occurred because he had been drugged.

On the morning of the fight, MacDonald was surprised to find out that Sayers would be his assistant in the corner, having been told that James Heenan would be fulfilling that role.

Quitting his New York home for the purer air of the west, he died at Green River Station, Wyoming Territory on October 28, 1873.