In December 1918 he was arrested along with his brother at Kilfinane. They were held in Athenry before escaping. During the Irish War of Independence, he headed the East Limerick Brigade of the Irish Republican Army. During the Irish Civil War, he opposed the Anglo-Irish treaty. He began teaching in a room in Tyrrellspass Castle, and even established a school named the Thomas Davis Secondary School, however the Department of Education refused to officially recognize the school.