Mortimer Moynahan was a leading figure in both the IRB and the Fenian Brotherhood. He was a founder of the Phoenix National and Literary Society and was influential in the early expansion of Fenianism. A confidant of the Fenian leader James Stephens, he rose to become, for a brief period, the leader of the Fenian Brotherhood in America. However, by the time of his death in 1881 he was largely overlooked and forgotten.

Moynahan was born in Carriganima, north of Macroom, Co. Cork, in the early 1830s. Like others of his generation, Moynahan witnessed first-hand the devastation of the Great Famine of 1845-52. On a more positive note, he benefited from an education at a local national school and afterwards he became a schoolteacher. In April 1856 he was dismissed from his teaching position, and this prompted him to change careers. So, in 1856 he found employment as a legal clerk in Skibbereen. After moving to Skibbereen he quickly became friends with Jeremiah O’Donovan Rossa and Daniel McCartie Jnr. In late 1856 discussions between Mortimer Moynahan, Jeremiah O’Donovan Rossa and others led to the formation of the Phoenix National and Literary Society in Skibbereen.
The Phoenix Society was an open organisation dedicated to the revival of the Irish national spirit. Writing about this organisation, Mortimer Moynahan stated that its aspiration was that similar organisations would be set up in every town and village in Ireland and that these societies might ‘as does our own body consist of Irishmen, professing Young Ireland politics.’ During 1857 the society adopted increasingly radical views and by the spring of 1858 it was near collapse.
In May 1858 James Stephens, leader of a new organisation the Irish Republican Brotherhood (IRB), arrived in Skibbereen. The IRB was a secret, oath-bound organisation, whose objective was to overthrow British rule in Ireland through military insurrection. Once in Skibbereen, Stephens swore Daniel McCartie into the new organisation. McCartie then swore in Jeremiah O’Donovan Rossa who, in turn, swore in Mortimer Moynahan. In a short time, the majority of the members of the Phoenix Society became sworn members of the IRB and the old format of the Phoenix Society ceased to exist.
The new organisation with Moynahan, O’Donovan Rossa and McCartie acting as the local leaders, quickly gained new members and spread to other areas, particularly Bantry and Kenmare. This expansion was aided by the fact that Moynahan was a senior clerk in the prominent legal firm of Timothy McCarthy-Downing and as a result he traveled widely in west Cork and south Kerry. The expansion of the IRB in this area made Moynahan, McCartie and O’Donovan Rossa well known figures within the organisation. While O’Donovan Rossa is the one remembered by history, in these early years there is evidence to indicate that it was Moynahan who was the most respected. For example, in his later memoirs John O’Leary stated that: ‘I am again reminded by [Thomas Clarke] Luby that, of those three, Moynahan was then and always, while the least noisy, much the most active.’
The activities of the IRB did not go unnoticed and throughout the autumn of 1858, the constabulary gathered evidence against the new movement. They also recruited the infamous informer O’Sullivan Goula to infiltrate the movement in Skibbereen. As a result, on 8 December 1858 twelve men were arrested in the town, including Moynahan, O’Donovan Rossa and McCartie. While most of those arrested were quickly released on bail, Moynahan and O’Donovan Rossa spent seven months in jail awaiting trial. In July 1859, a compromise was reached and in return for pleading guilty the remaining prisoners were immediately released on an understanding of future good behavior.

As Moynahan and O’Donovan Rossa rebuilt their lives in Skibbereen, it appeared that the IRB as a movement was dead and constitutional nationalists, such as Bantry-born A.M. Sullivan, took the initiative. In April 1860, he suggested a national petition to seek a plebiscite on legislative independence for Ireland. Though they were initially skeptical of this initiative, eventually both Moynahan and O’Donovan Rossa became heavily involved in local efforts to gather signatures and collected 4,785 signatures.
Despite some setbacks the IRB continued to exist and in January 1861, John O’Mahony the leader of its sister organisation, the Fenian Brotherhood in America, visited Ireland. While here O’Mahony undertook a tour of IRB strongholds, including west Cork. Here he was met by O’Donovan Rossa, McCartie and Moynahan and he spent several days in Skibbereen. Later James Stephens undertook his own tour of IRB units. This included a visit to Skibbereen where John O’Leary later commented that he encountered ‘the inevitable Rossa, Dan McCartie and Morty Moynahan’. A rejuvenated IRB, combined with a series of poor harvests, meant that from 1861 onwards the IRB’s membership expanded nationwide. In the Skibbereen area Moynahan, O’Donovan Rossa and McCartie remained at the helm, though by now O’Donovan Rossa was the best known of the three. To foster the continued growth of the local movement the three leaders organised a series of public demonstrations which were unique within the IRB. The largest of these demonstrations was a rally in support of a Polish rebellion against the Russian Empire, which was organised for March 1863. However, in May 1863 O’Donovan Rossa left Skibbereen for good. First he went to America and later in 1863 he returned to Ireland to become the manager of the IRB’s newspaper, the Irish People. Mortimer Moynahan remained in Skibbereen where he continued as a local IRB leader and he also helped fund, distribute and contribute to the Irish People.

Mortimer Moynahan was arrested for a second time in September 1865 when he was visiting Dublin. On this occasion he was detained in a case of mistaken identity for his brother Michael, who was a clerk in the Irish People newspaper. After two months in jail, Moynahan was released on bail and his case was never brought to trial. After his release, in the absence of many imprisoned IRB leaders, he was appointed interim leader of the IRB in Cork city and county. In his new role he was present at the meeting of IRB leaders in February 1866 where the decision to postpone a planned rebellion was made. Following the postponement of the rising, James Stephens departed Ireland for America. Before leaving he appointed Mortimer Moynahan as his liaison with the movement in Britain. To fulfill these duties Moynahan took up residence in London, though after a short period he moved to Paris to fulfill a similar role there. After spending three months in Paris, Moynahan followed Stephens to America.
While in America Mortimer Moynahan was active in the Fenian Brotherhood and on 6 January 1867 after the removal of Stephens as leader of the movement, he was appointed interim leader of the Fenian Brotherhood in America. He maintained that position until elections were held on 27 February 1867 and Anthony A. Griffin was elected as the new leader of the American organisation. During his brief period as leader, Moynahan attempted unsuccessfully to persuade John Mitchel to lend his name to the continuing efforts of the Fenian Brotherhood to raise funds for a rebellion in Ireland. Moynahan’s failure to persuade Mitchel does not appear to have diminished his standing within the Fenian Brotherhood and after his time as leader he was appointed financial secretary of the movement. In this role, his main task was to raise funds through the continued sale of ‘bonds of the Irish Republic’. In January 1871, when O’Donovan Rossa arrived in America, Moynahan wrote to his old friend warning him to steer clear of local American politics. By then it appears Moynahan had no official position in the Fenian Brotherhood.
The following years where difficult ones for Mortimer Moynahan. In 1861 he had married Mary Cunningham of Skibbereen and the couple had four children, three daughters and a son, while still in Ireland. In America, the family settled in Cherry Street on lower Manhattan, where it grew further with the arrival of another son in 1868. After his time at the helm of the Fenian Brotherhood, Moynahan worked as a journalist, but he was unable to find regular employment. On 13 July 1874 newspapers reported that Moynahan’s wife had been discovered dead in their apartment and he was also close to death. The story that emerged was a tragic one. It appears that, with Mortimer unable to find employment, the Moynahans had sent their three daughters to a convent, keeping their two sons with them. Afterwards, the newspapers reported that the Moynahan boys were being cared for by friends, that Moynahan himself had been committed to Bellevue Hospital for the insane, where O’Donovan Rossa was among the first to visit him. Despite the initial reports that claimed Moynahan was close to death, he survived and appears to have made a good recovery. By late 1875 he was once more involved in Irish-American politics, when he was made secretary of an organisation that campaigned for the release of Edward O’Meagher-Condon, who had been sentenced to death with the Manchester Martyrs, but had his sentence commuted to life imprisonment as he was an American citizen. He was also involved in helping his old friend O’Donovan Rossa organise the day-to-day affairs of the Fenian Brotherhood. A letter, dated 12 April 1876, to Mortimer from his brother Michael, indicates that by then he was reunited with his children as Michael stated that ‘I am very glad to hear the children are getting on so well’.
In 1876 following the success of the Catalpa rescue of Fenian prisoners in Australia, plans were considered to free other Fenian prisoners including Edward O’Meagher-Condon, who at the time was imprisoned on Spike Island. Part of the preparations was to send Mortimer Moynahan to Ireland to organise the rescue efforts there, so sometime in 1876 Moynahan returned home. However, the rescue plans came to nothing and life for Moynahan did not improve after his return to Ireland. In June 1879, a letter in the Irishman newspaper from a doctor at the Cork District Lunatic Asylum stated that he had been a patient in that institution for the previous two years. Mortimer Moynahan died in Cork District Lunatic Asylum on 10 May 1881. His death was not recorded in any of the local or national newspapers.