MacManus's friend, Charles Gavan Duffy, stated that he was orphaned when his father, who was a catholic soldier, was killed whilst serving with his regiment.
Duffy went on to say that MacManus was then reared in the soldier's hospital in the Phoenix Park as a Protestant,[1] the Royal Hibernian Military School.
[1] MacManus's first contribution to the Royal Hibernian Academy (RHA) was in 1835, becoming a member of the Belfast Association of Artists in 1836, exhibiting four portraits with them.
After receiving initial praise followed by a salary increase at the suggestion of the governors, difficulty erupted between MacManus and the school's committee of management.
However, the department felt that academic standards were suffering due to a decline in MacManus's health, and pressured the RDS into removing him.