O'Mara, James (1873–1948), bacon merchant, politician, and Sinn Féin fund-raiser, was born 6 August 1873 in Limerick, eldest surviving son among seven sons and five daughters of Stephen O'Mara (qv), bacon merchant from Limerick, and his wife, Ellen, daughter of Patrick Pigott, publican, and Nell Pigott (née Ebrill). He was educated at Clongowes Wood College (1888–91). On leaving school (1892) he joined the family business to learn the bacon trade while pursuing his degree simultaneously. However, in 1893 his father's brother, Jim, the company's agent in London, died. Although it meant postponing his studies O'Mara willingly moved to London to take over as London agent for the family. He initially found the work dispiriting but by spring 1894 he began to see a steady increase in sales. In 1898 he finally found the time to sit and obtain his BA from the RUI. By 1900 the agency had grown considerably, and in the same year he successfully stood for parliament as a United Irish League candidate for Kilkenny South. When he took his seat at Westminster he was the youngest MP.
In 1902 he travelled to Rumania, where he secured a lucrative agency for the firm, and the following year (1903) he seconded the bill proposed by William Redmond (qv) to make St Patrick's day a holiday in Ireland. He was reselected to stand in the election of 1906 but his acceptance speech marked a clear shift in his views towards those of the fledgling Sinn Féin movement. Despite the advice of his father, who counselled that he should obey the party leader, he became restless with the lack of progress on home rule under John Redmond (qv). He believed that Irish MPs were becoming too attached to Westminster and too detached from the reality of the situation in Ireland. On 15 June 1907 he resigned his seat and left the Irish party in protest at the limited provisions of the Irish councils bill; later that year he joined Sinn Féin.
In 1914 he returned to Dublin to manage Donnelly's bacon factory, which his father had purchased in 1906, and became a generous benefactor to Sinn Féin and the newspaper of the same name run by Arthur Griffith (qv). In 1918 he became more centrally involved with the movement when he was appointed director of finance and director of elections for Sinn Féin. His formidable administrative skills helped to bring about the landmark result of the December 1918 election as well as his own election to the first dáil as deputy (1918–21) for Kilkenny South. In October 1919, when Eamon de Valera (qv) requested that O'Mara join him in the USA to help build up a fund-raising organisation, O'Mara was denied an exit visa by the authorities and had to travel as a stowaway on the Lapland. In America he created and ran the fund-raising machine that operated the bond drive to raise a national loan, of which he became a trustee, for the Irish Republic. De Valera toured the country to attract publicity for the bond drive and wherever he went O'Mara organised rallies and set up local fund-raising committees. His efforts eventually realised more than $3 million for the Irish cause.
Before de Valera returned to Ireland at the end of 1920 he made proposals to raise a further loan of $20 million and to impose a levy on the members of the American Association for Recognition of the Irish Republic (AARIR). O'Mara rejected the levy, insisting that it would be an insult to charge a levy while also asking for a loan. When de Valera returned to Ireland he wrote to O'Mara on several occasions stressing the need to curtail the costs of the American operation because the funds were needed in Ireland. This irritated O'Mara intensely because he had been ruthless in capping expenditure, to the extent that he had funded his personal expenses out of his own pocket to the sum of £10,000. What soured the relationship irrevocably was de Valera's insistence on pushing through his proposal of both a new loan and a levy on the members of the AARIR. O'Mara tendered his resignation as a trustee and announced his intention not to stand at the next election. He told Harry Boland (qv) that he would no longer work under de Valera, whose interference, he believed, would destroy the aid coming from America. Returning to Ireland in July 1921, he was replaced as fund-raiser and special envoy to America by his younger brother, Stephen O'Mara (qv).
Back in Ireland he initially concentrated on his business interests. When the treaty was signed in December 1921 he gave it his whole-hearted support and showed his loyalty to the new regime by loaning Arthur Griffith and Michael Collins (qv) £2,000 to cover the expenses of their 1922 election campaign. In 1924 he briefly returned to politics when he was elected to the dáil as Cumann na nGaedhal deputy (1924–7) for Dublin South, but he refused a post in the cabinet of W. T. Cosgrave (qv). He finally left politics in 1927 and once again returned to the family firm before retiring in the early 1930s when he sold Donnelly's bacon factory to his brother, Alphonsus O'Mara.
During his time in London he lived at ‘Dunlica’, College Road, Dulwich. In Dublin he lived (1914–25) at 43 Fitzwilliam Place and later (1925) at ‘The Grove’, Killiney, Co. Dublin. He died 21 November 1948 in Dublin.
He married (28 April 1895) Agnes, daughter of Blennerhassett Cashel, railway clerk and later stationmaster at Mallow; they had one son and six daughters.