Campbell, David R. (1875–1934), trade unionist, was born in Belfast. Coming from a protestant and Orange background, Campbell was a member of the Belfast Socialist Society and of the Belfast Trades Council, where he represented insurance agents. He was elected president of the BTC in 1909, and became an executive member (1909–14) of the Irish Trades Union Congress, its president (1911), and treasurer (1913–18). These years were dominated by the turbulent figure of James Larkin (qv), whom Campbell supported, and the founding of the Irish Transport and General Workers Union. At the 1909 congress Campbell favoured the admission of the newly formed ITGWU to Congress and the establishment of the Irish Labour Party. When the vote went against Larkin and the ITGWU, Campbell proposed a committee, taken from the congress executive, to look into the question and also to investigate the charges that the National Union of Dock Labourers were blacklegging on the ITGWU in Belfast. This gave Larkin time to gather support. The committee's report found the ITGWU to be a bona fide trade union and recommended its admission. In 1910 James Connolly (qv) was in Belfast, where, with Campbell's support, he established a branch of the Socialist Party of Ireland. Campbell attended the Easter 1910 SPI conference in Dublin, the first all-Ireland gathering of socialists and the setting for the Walker–Connolly debate on the role of nationalism in the socialist movement. During the third home rule crisis, sectarianism cut into the foundations of trade unionism in Belfast. Campbell acted on a deputation representing catholic workers expelled from Harland & Wolff in 1912. He tried his best for them, but was unable to move the Belfast Trades Council, which, though it acted as the coordinator of Belfast trade unions, did nothing for the expelled workers.
Campbell was involved further with Connolly's attempts to build an Irish working-class party, initially in the Independent Labour Party of Ireland and then in the political wing of the Trades Union Congress, the ILP&TUC. Campbell was elected to the executive of the ILP&TUC in June 1914. He supported home rule but opposed the prospect of partition at the 1914 congress. He travelled as a member of the Irish Labour Party to the USA on a fund-raising tour to allow the party to contest a home rule election. The declaration of war (August 1914) opened up differences between Campbell, who believed that the defeat of Germany would further the cause of democracy, and Connolly, who remained an isolated anti-war voice in socialist circles.
In the immediate aftermath of the 1916 rising the leadership of the ITGWU fell to Campbell and Thomas Johnson (qv). They sought the return of seized ILP&TUC papers and the release of imprisoned trade union leaders. Campbell continued to oppose partition in a meeting with Lloyd George (July 1916), wanting the question to be deferred until after the war. On this he was not supported by the increasingly republican ITGWU. Though opposed to conscription in April 1918, he did not like what he considered the unduly alarmist tone of the party and congress on the issue, and did not stand again for the congress executive. He opposed the party decision not to contest the 1918 election. After 1918 Campbell remained active in Belfast on the trades council: he remained secretary of the life assurance workers and led the labour group on the corporation. In 1919–20 he worked for the Ulster extension committee of proportional representation in Ireland, lecturing and explaining PR to Belfast voters. In the 1920 local election, of twenty-two labour candidates in Belfast ten were returned. But the 1920 expulsions cowed the labour group, who feared being associated with Sinn Féin. No labour speakers attended the special corporation meeting called for 31 July 1920 to discuss the expulsions; not even Campbell, though he had requested the meeting.
In later years Campbell was given an appointment with the Royal Liver Friendly Society but resigned (1928) when he was called to the Northern Ireland bar. He specialised in industrial and workplace injuries and compensation law. Campbell died suddenly at his home in Belfast, aged 59 years, on 14 January 1934 leaving a widow and four children. His career demonstrates that for many socialists in early twentieth-century Ireland the labour question was not only more relevant than the national question but also seemed more revolutionary; and that labour issues offered popular politics free from the cancer of sectarianism.