Complex sentence: Soon after in August 1971, Devine became of volunteer of the Official IRA and in 1974 left the Officials and joined the INLA and was also a founding member of the Irish Republican Socialist Party (IRSP) in Derry.
Split into simpler sentences: Soon after in August 1971, Devine became a Volunteer in the Official IRA and in 1974 left the Officials and joined the INLA. He was also a founding member of the Irish Republican Socialist Party (IRSP) in Derry.