O’Hara joins Na Fianna Éireann in 1970 and, in 1971, his brother Sean is interned in Long Kesh Prison. In late 1971, at the age of 14, he is shot and wounded by a soldier while manning a barricade. Due to his injuries, he is unable to attend the civil rights march on Bloody Sunday but watches it go by him in the Brandywell Stadium, and the events of the day have a lasting effect on him.
In October 1974, O’Hara is interned in Long Kesh Prison, and upon his release in April 1975 he joins the Irish Republican Socialist Party (IRSP) and INLA. He is arrested in Derry in June 1975 and held on remand for six months. In September 1976, he is arrested again and once more held on remand for four months.
On May 10, 1978, O’Hara is arrested on O’Connell Street in Dublin under section 30 of the Offences Against the State Act, and is released eighteen hours later. He returns to Derry in January 1979 and is active in the INLA. On May 14, 1979, he is arrested and is convicted of possessing a hand grenade. He is sentenced to eight years in prison in January 1980.
On Thursday, May 21, 1981 at 11:29 PM, Patsy O’Hara dies after 61 days on hunger strike, at the age of 23. In accordance with his wishes, his parents do not get him the medical intervention needed to save his life. His corpse is found to be mysteriously disfigured prior to its departure from prison and before the funeral, including signs of his face being beaten, a broken nose, and cigarette burns on his body.
O’Hara’s mother, Peggy O’Hara, is a candidate in the 2007 Northern Ireland Assembly election in the Foyle constituency. She is not elected, but she is one of the more successful dissident republican candidates opposed to the new policy of the Sinn Féin leadership of working with the Police Service of Northern Ireland (PSNI), and wins 1,789 votes. On the eve of the election, over 330 former republican prisoners write a letter to the Derry Journal endorsing her campaign.