Hayes joined the IRA and was on the IRA Army Council in January 1939 when it declared war on the British government. When IRA chief of staffSeán Russell departed on IRA business to the United States, Hayes became IRA chief of staff. His time in office was marred by controversy and it is widely believed that he served as an informer to the Garda Síochána. Hayes had sent a plan for the invasion of Northern Ireland by German troops to Germany in April 1940. This plan later became known as Plan Kathleen. He is also known to have met with German agent Hermann Görtz on 21 May 1940 in Dublin shortly after the latter's parachuting into Ireland on 5 May 1940 as part of Operation Mainau. Hayes is known to have asked Görtz for money and arms to wage a campaign in Northern Ireland, although shortly after this meeting the original Plan Kathleen was discovered. The discovery of the plan led to the acceleration of joint British and Irish military planning for a German invasion known as Plan W. Another meeting on 15 August 1940 on Rathgar Road, Dublin organised by Hayes and attended by senior IRA men Paddy McGrath, Tom Harte and Tom Hunt, was also raided by the Garda Síochána. McGrath and Harte were both arrested and tried by Military Tribunal, established under the Emergency Powers Act 1939. They challenged the legislation in the High Court, seeking a writ of habeas corpus, and ultimately appealed to the Supreme Court. They were represented in the courts by Seán MacBride. The appeal was unsuccessful, and they were executed by firing squad at Dublin's Mountjoy Prison on 6 September 1940. On 30 June 1941, Northern-based IRA men kidnapped Hayes, accusing him of being a spy. By his own account, he was tortured and "court-martialled" for "treason" by his comrades, and would have been executed, but he bought himself time composing an enormously long confession. He managed to escape in September 1941, and handed himself in to the Garda for protection. The Officer Commanding of the IRA's Northern Command, Seán McCaughey, was convicted on 18 September 1941 of the kidnapping. After a long hunger and thirst strike in Portlaoise prison, McCaughey died on 11 May 1946. Hayes was later sentenced to five years' imprisonment by the Special Criminal Court on account of his IRA activities. Within IRA circles, Hayes is still considered a traitor and an informer. One of the main allegations against him was that he informed the Garda Síochána about IRA arms dumps in Wexford. However, this was later blamed on a Wexford man named Michael Deveraux, an officer of the Wexford Battalion of the IRA who was subsequently abducted and executed by an IRA squad in County Tipperary on Hayes’ orders. George Plant, a Protestant IRA veteran, was later executed in Portlaoise for Devereux's murder.
Later life
After his release, Hayes resumed his clerical position at Wexford County Council. He died in Enniscorthy on 28 December 1974.
