O'Hegarty, Sean (1881–1963), republican, was born 21 March 1881 at 26 Evergreen Street, Cork, second and younger son of John Hegarty, plasterer and Fenian (d. 1888), and his wife Katherine (née Hallahan), who worked as a domestic servant to support her family after her husband's death. Patrick Sarsfield O'Hegarty (qv) was his elder brother. O'Hegarty was educated at the Christian Brothers’ North Monastery School, and in 1902 he became a sorter at Cork post office, later rising to postal clerk. At the same time he became active in various aspects of the Irish Ireland movement. He was captain of the head post office hurling team (whose members included his brother, Patrick, and J. J. Walsh (qv)); in later life he remained active in the GAA as an administrator and served on the Cork county board and junior board in 1923.
O'Hegarty was active in the Gaelic League, becoming a founder member of the O'Growney branch in 1907 and a member of the league's executive after it was taken over by separatists in 1915. Most importantly for his future career, he joined the separatist Celtic Literary Society in 1905, and when the IRB was reorganised in Cork in 1906 he became centre of the first local circle (recruited from post office employees). Like many early Irish Irelanders, he had a somewhat puritanical mindset: he was a lifelong non-smoker and total abstainer (he suggested that the treaty negotiations of 1921 went as they did because the Irish delegates drank more than was good for them).
In 1910 O'Hegarty became chairman of the Cork branch of Sinn Féin, but in 1911 he and other Cork republican activists (including Tomás MacCurtain (qv)) withdrew from the party because of their opposition to the dual monarchist policy of Arthur Griffith (qv); they founded a local slua of Fianna Éireann. In December 1913 O'Hegarty was one of the founding members of the Cork section of the Irish Volunteers; in June 1914 he was appointed assistant secretary of the Cork Volunteer executive, and he also served on the Volunteers’ military council. After the outbreak of the war he was assigned to reconnoitre possible landing sites for an invasion force.
In October 1914 O'Hegarty was dismissed from his employment with the post office after he refused to accept a (politically motivated) wartime transfer to Britain. He was later excluded from Cork city under the Defence of the Realm Act. He moved to Ballingeary, where he worked as a labourer, but he was then excluded from Cork county as well. He settled at Enniscorthy, Co. Wexford, where he lived with Larry de Lacy. He was arrested on 24 February 1915 and tried on separate charges of possession of explosives and of circulating notices calling on farmers to assist the Germans if they landed. He was acquitted on both counts – the first on the grounds that the explosives might have belonged to de Lacy, and the second after a retrial, the original jury having failed to reach agreement (the second acquittal may have been due to jury intimidation). Shortly before the Easter rising O'Hegarty returned to Ballingeary to take command of the Bandon and Ballingeary companies of Volunteers.
In 1917 O'Hegarty returned to Cork city to become vice-commandant of Cork no. 1 brigade of the IRA. In August 1917 he applied for the position of storekeeper at the Cork workhouse, and was elected unanimously after several other candidates withdrew. Allegations of intimidation led to an official inquiry into the appointment, but he was confirmed in the post as the findings were inconclusive. O'Hegarty subsequently clashed with the poor law guardians over allegations of corruption and malpractice; in January 1920 the local government board held an official inquiry into O'Hegarty's allegations of corrupt practices and conflict of interests in the workhouse administration. Although the members of the board were O'Hegarty's political opponents, they upheld most of his complaints and significant improvements resulted. O'Hegarty spent the rest of his career in this position, retiring as head storeman of St Finbarr's Hospital (as the workhouse had been renamed).
At the same time O'Hegarty (nicknamed ‘the Joker’ by friends) emerged as the key IRB figure and militant within the Cork IRA. While Terence MacSwiney (qv) had always disapproved of the IRB because he thought secrecy bred demoralisation, and MacCurtain allowed his membership to lapse, believing the secret organisation to be no longer necessary after the 1916 rising, O'Hegarty had retained his membership and became Cork county centre. This allowed the growth of a second, informal, command structure, centred on the IRB, whose key figures were O'Hegarty and the intelligence officer Florence O'Donoghue (qv). Between 1917 and 1920 (when O'Hegarty assumed full control of the Cork no. 1 brigade after the deaths of MacCurtain and MacSwiney), ‘O'Hegarty's mob’ were responsible for most IRA actions in the city. O'Hegarty, like many other local activists, blamed MacCurtain and MacSwiney for the failure to launch an effective rising in Cork in 1916 and for the subsequent loss of the city Volunteers’ arms (he subsequently made a point of instructing his men to defend their arms at all times); the three men nevertheless remained on good personal terms.
As a result of incidents that exposed the dual command structure in April and May 1918 (including an explosion at a clandestine bomb factory) O'Hegarty was replaced as vice-commandant by MacSwiney and returned to the ranks as an ordinary Volunteer. However, O'Hegarty retained his IRB position and authority, and his prestige was increased by such actions as the rescue of the Volunteer Donnchadh MacNeilus from Cork jail on 11 November 1918. Despite his own demotion, his ally O'Donoghue remained in place as brigade adjutant and O'Hegarty was reinstated as vice-commandant when MacSwiney became commandant after MacCurtain's assassination in March 1920. After MacSwiney's arrest on 12 August 1920, O'Hegarty (who had also been arrested but was released) became unchallenged leader of Cork no. 1 brigade.
The brigade area covered large areas of mid- and east Cork, stretching from Youghal and Ballycotton in the east to the Inchigeela area in the west. O'Hegarty helped to plan and oversee flying column activity in this area, including a major ambush at Coolnacaheragh (also known as Coolavokig) on 25 February 1921, where he commanded in person; he travelled with the flying column, sending messages to O'Donoghue (who oversaw events in the city) by couriers using word of mouth. Although he was an able commander, his ‘decisive, quick-witted and sharp-tongued' personality (Borgonovo, O'Donoghue, 29) had its drawbacks; his harsh manner made his subordinates reluctant to dispute his decisions, even when these were not soundly based – except for a few intimates, his men stood in awe of him. (O'Hegarty's sense of humour is reflected in his often-quoted remark to O'Donoghue that when the war ended their occupation would be gone – ‘I'll go back to the poorhouse, and I suppose you'll go back to selling collars again’ (Borgonovo, O'Donoghue, 154).)
O'Hegarty took personal responsibility for the killing of several alleged spies and informers in the area. Borgonovo argues convincingly that these activities were largely based on accurate intelligence obtained by O'Donoghue through his wife (who did secretarial work at the British military headquarters in Cork). He notes that ‘the fierce Sean O'Hegarty’ was sometimes impatient with O'Donoghue's insistence on deferring killings if there was reasonable doubt of guilt; further he states that a British soldier who supplied the IRA with information claimed that though O'Hegarty eliminated civilian informers he neglected to pursue informers within the IRA (Borgonovo, Spies, 6, 30). O'Hegarty was also ultimately responsible for the controversial shooting of Georgina Lindsay and her chauffeur in March 1920 after she warned crown forces about a planned IRA ambush, leading to the capture and execution of Volunteers. Although the general command of the IRA made known its disapproval of the shooting (Mrs Lindsay had been taken hostage in an unsuccessful attempt to prevent the execution of captive Volunteers), O'Hegarty took full responsibility and justified his action by the necessities of war.
O'Hegarty opposed the treaty. In December 1921 he circulated to all TDs in the brigade area a demand that they vote against it, informing them that support for it would constitute treason against the republic (and, by implication, incur the penalty of death). This action was widely criticised as an attempt to intimidate the dáil. He subsequently had pro-treaty meetings forcibly dispersed and destroyed the entire print run of a pro-treaty pamphlet by Alfred O'Rahilly (qv). On 29 March 1922 he organised the capture of the British ship Upnor carrying arms and ammunition from Cobh to Woolwich; this single exploit supplied much of the arsenal used by republican forces in Munster during the civil war.
On 9 April 1922 O'Hegarty was elected to the sixteen-member army executive established by the anti-treaty IRA; however, he subsequently established peace talks in order to avoid civil war, organising discussions in a committee of ten officers (five from each side) who put forward proposals for the creation of a unity government and a unified army. On 3 May O'Hegarty led a delegation of officers to the dáil, and was allowed to address it on the need to avert civil war. He subsequently acted as a mediator between the two sides, in conjunction with other officers, including O'Donoghue. On the outbreak of the conflict he declared his intention to remain neutral, and became a leading member of the ‘neutral IRA’ group (founded December 1922), which tried to bring about a compromise peace. He was afterwards critical of the Free State government for (as he saw it) frustrating these efforts, though Liam Lynch (qv) also actively discouraged contacts between them and his officers.
Much of O'Hegarty's later life was concerned with the politics of republican commemoration; after the death of his wife he became an ‘almost nightly’ visitor to Florence O'Donoghue's home, discussing the past for hours. He engaged in a long correspondence with the papal nuncio in the 1920s and 1930s in an attempt to have the excommunication inflicted on the Cork IRA during the war of independence by Bishop Daniel Cohalan (qv) formally nullified by higher authority. (Although Borgonov describes him as an atheist during the war of independence period (O'Donoghue, 233), O'Hegarty appears, unlike his brother, to have reverted to catholicism in later life.) In 1958 he brought about the repatriation of the remains of the IRA chaplains Father Dominic O'Connor and Father Albert Bibby (1877–1924) after lengthy negotiations with the Capuchin order of which they were members, and he chaired the committee which erected a permanent monument to them at the republican plot in St Finbarr's cemetery, Cork (unveiled 1963).
On 1 February 1912 O'Hegarty married Maghdalen (Mid) Ní Laoghaire (d. 1940), who became a prominent Cork Cumann na mBan activist; her uncle was the writer Peadar Ó Laoghaire (qv). They had no children. Sean O'Hegarty died 31 May 1963 at the Bon Secours Hospital, Cork. The Crawford Art Gallery, Cork, has a bust by Breeda Lucci. His career encapsulates the tensions and repercussions of the military struggle on the wider Sinn Féin movement during the war of independence period.