His maternal grandfather had been a United Irishman. While he was still a child, the family moved to Wexford, where he received an informal education. In 1842, McGee left Ireland and travelled to North America where he joined the staff of the Boston Pilot, a Catholic newspaper. Two years later, at the age of 19, he was editor of the paper, using his position to lobby for Irish independence and the rights of Irish Catholic immigrants. He also then supported the American annexation of Canada.
In 1845 McGee returned to Ireland to work at the Freeman’s Journal, and later the Nation. He married Mary Teresa Caffrey at Dublin on July 13, 1847. He became involved in the Young Ireland movement and was in Scotland, seeking support for an Irish rising when the Irish rebellion of 1848 failed.
He was forced to flee to the United States, where he continued to edit newspapers (including his own, the Nation), agitate for Irish independence, and devise projects for the betterment of Irish immigrants. When McGee’s projects failed to gain support, he moved to Montr