He was a close personal friend of Arthur Griffith and an early member of Sinn Féin, serving on its national executive from 1909 to 1912.

[1] He joined the Irish Volunteers, and in 1915 he was arrested and imprisoned for three months for a speech in which he urged Irishmen not to fight in World War I.

[1] On 3 February 1919 he escaped from Lincoln Jail in England along with Seán McGarry and Éamon de Valera.

[5] At the 1918 United Kingdom general election he stood in Tyrone North-East, but an electoral pact brokered by Cardinal Michael Logue allocated the seat to the Irish Parliamentary Party and it was not contested by Sinn Féin.

[8][non-primary source needed] He became a member of Cumann na nGaedheal but left the party and resigned from his seat on 30 October 1924 along with seven other TDs in opposition to the Government's actions to the so-called Irish Army Mutiny.