Born in Fredericktown, Ohio, Chamberlain's father, Uriah, was an anti-slavery activist and a founder of Oberlin College.
Isaac served with the 18th Pennsylvania Cavalry Regiment during the American Civil War, while also working as a correspondent for newspapers including the Erie Gazette and The Cleveland Leader.
[1] Chamberlain joined the Knights of Labor, and in 1897, he was elected as General Worthy Foreman of the union, the second-most senior position.
[2] In 1898, he opposed the American occupation of Cuba, and also the idea of a large standing army, which he feared would be used against striking workers.
Parsons did not attend, and the executive voted to expel him from the union, with Chamberlain becoming General Master Workman.