Hughes joined the
Irish Republican Army in 1969, sided with the Provisional faction in the split of 1969–70, and was "on the run" in Belfast by 1970. From 1970 to 1972 Hughes was involved in a number of attacks on British soldiers and bank robberies to raise funds for the republican movement. Hughes was key to the IRA's early activity in Belfast against the British Army, especially in and around the
Falls Road area of Belfast, sometimes carrying out along with his unit as many as five operations a day against either the
British Army or the
RUC. Hughes described his normal day during that period as "you would have had a call house [a safe meeting place] and you might have robbed a bank in the morning, done a float [gone out in a car looking for a British soldier] in the afternoon, stuck a bomb and a booby trap out after that, and then maybe had a gun battle or two later that night." After the IRA-British truce of 1972 broke down in July, Hughes was an IRA commander during the
Battle of Lenadoon, which quickly spread to other parts of Belfast. A number of civilians, British soldiers, and both Republican and
Loyalist volunteers were injured or killed. As Officer Commanding (OC) of the
Provisional IRA Belfast Brigade, he was the main organiser of
Bloody Friday, the biggest bombing attack ever carried out by the organisation in Belfast. On 21 July 1972, the IRA exploded 22 bombs all over the city, leaving nine people dead, including two British soldiers, an
Ulster Defence Association (UDA) member, two teenage boys, and a mother of seven; 130 people were injured. Hughes regarded the operation as a disaster, as he explained in an interview set up by
Boston College: I was the operational commander of the "Bloody Friday" operation. I remember when the bombs started to go off, I was in Leeson Street, and I thought, "There's too much here". I sort of knew there were going to be casualties, either [because] the Brits could not handle so many bombs or they would allow some to go off because it suited them to have casualties. I feel a bit guilty about it because, as I say, there was no intention to kill anyone that day. I have a fair deal of regret that 'Bloody Friday' took place ... a great deal of regret ... If I could do it over again I wouldn't do it. On 19 July 1973, Hughes was arrested on the Falls Road along with
Gerry Adams (later President of
Sinn Féin between 1983 and 2018) and Tom Cahill. They were interrogated for more than twelve hours at the
Springfield Road Royal Ulster Constabulary (RUC) barracks and later at
Castlereagh, before being transported to
Long Kesh. On 8 December, Hughes escaped inside a rolled-up mattress in the back of a
dustcart, and fled across the border to
Dublin. After ten days he returned to Belfast after assuming a new identity, becoming a travelling toy salesman named "Arthur McAllister". For five months, Hughes lived in Myrtlefield Park near
Malone Road, and was believed to be the new O/C of the IRA in Belfast following the arrest of
Ivor Bell in February. On 10 May 1974, Hughes was arrested following a tip-off, and the house was found to contain a submachine gun, four rifles, two pistols and several thousand rounds of ammunition. Hughes was subsequently sentenced to fifteen years in prison. Three years after his arrest, Hughes was involved in a fracas and received an additional five-year sentence for assaulting a prison officer. As he was convicted after 1 March 1976, Hughes was transferred from the compounds to the H-Blocks and lost his
Special Category Status. He refused to wear a prison uniform and joined the
blanket protest. Shortly after arriving in the H-Blocks, Hughes became the OC of the IRA prisoners, and in March 1978 ordered the prisoners to begin the
dirty protest. Whilst in prison, Hughes formed a friendship with
Shankill Butchers and
Ulster Volunteer Force (UVF) member
Robert Bates, who later foiled a UVF plot to assassinate Hughes. ==Hunger strike==