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 O/C of the IRA prisoners, and in March 1978 ordered the prisoners to begin the dirty protest.