The Volunteers were local militias raised by local initiative in Ireland in 1778. Their original purpose was to guard against invasion and to preserve law and order at a time when British soldiers were withdrawn from Ireland to fight abroad during the American Revolutionary War and the government failed to organise its own militia. Taking advantage of Britain's preoccupation with its rebelling American colonies, the Volunteers were able to pressure Westminster into conceding legislative independence to the Dublin parliament. Members of the Belfast 1st Volunteer Company laid the foundations for the establishment of the United Irishmen organisation. The majority of Volunteer members however were inclined towards the yeomanry, which fought and helped defeat the United Irishmen in the Irish rebellion of 1798.

The Society of United Irishmen was a sworn association, formed in the wake of the French Revolution, to secure representative government in Ireland. Despairing of constitutional reform, and in defiance both of British Crown forces and of Irish sectarian division, in 1798 the United Irishmen instigated a republican rebellion. Their suppression was a prelude to the abolition of the Irish Parliament in Dublin and to Ireland's incorporation in a United Kingdom with Great Britain.