[1] At age sixteen he enlisted as a rifleman in the Pennsylvania state troops and marched with Benedict Arnold's expedition to Quebec in 1775.
Henry began to study law and, after clerking for Stephen Chambers, a prominent Lancaster attorney, he was admitted to the bar in 1785.
The eighth and eldest, Stephen Chambers Henry, was "for good causes...absolutely exclude[d] and disinherit[ed]" in his father's will.
[3] John Joseph Henry's career as a lawyer and judge was cut short by the recurrence of the injuries that he had suffered during the march on Quebec.
In his final years he wrote An Accurate and Interesting Account of the Hardships and Sufferings of That Band of Heroes, Who Traversed the Wilderness in the Campaign Against Quebec in 1775, published in 1812 after his death.