Mac Curtain, as he would later be known, was active in a number of cultural and political movements beginning around the turn of the 20th century. He joined the Blackpool, Cork branch of Conradh na Gaeilge (the Gaelic League), becoming its secretary in 1902. He had interests in music, poetry, history, archaeology and Irish history. He worked in his early career as a clerk, and in his free time taught Irish. In 1911 he joined Fianna Éireann, and was a member of the Irish Volunteers.