Sinn Féin for nine years. (It merged with two other organisations to form Fine Gael in 1933.) Anti-Treaty Sinn Féin members continued to boycott the Dáil. At a special "Ard Fheis" in March 1926, de Valera proposed that elected members be allowed to take their seats in the Dáil if and when the controversial Oath of Allegiance was removed. When his motion was defeated, de Valera resigned from Sinn Féin; on 16 May 1926, he founded his own party, Fianna Fáil, which was dedicated to republicanising the Free State from within its political structures. He took most Sinn Féin TDs with him.
Fianna Éireann been an outstanding Fianna officer for years. After internment he got married and eventually fell on hard times. In his own words, he was compromised by the Free State Special Branch and agreed to become an agent for them within the republican movement. He was eventually exposed by the Fianna Intelligence Officer, Frank Sherwin in 1926. Two former Fianna members made an attempt on his life in 1928, but Harling escaped and actually shot dead one of his attackers, Tim Coghlan of Inchicore. Harling was secreted out of the country by the Special Branch and ended up in the US