Allen, John (c.1780–1855), United Irishman and French army officer, was born in Dublin, son of Christopher Allen, dyer, of 44 Pimlico in the Liberties district, and in the early 1790s a member of the Dublin Society of United Irishmen. He went into the woollen-drapery trade and in 1803 was in business with John Hickson as a men's mercer at 36 College Green. A United Irishman, he was one of the group led by Arthur O'Connor (qv) who set off for Paris to deliver an address to the French directory only to be arrested (28 February 1798) at Margate, Kent, and put on trial at a special commission at Maidstone for high treason (21–2 May). His purported role was servant to ‘Captain Jones’, in reality James Coigly (qv), who alone was convicted and hanged. Allen became a confidant of Robert Emmet (qv), accompanied him, it was said, to Cadiz (1800), and played an important role in the brief insurrection that broke out in Dublin on 23 July 1803. Allen & Hickson's premises were used by the rebels on that day. A reward of £300 was offered by the government for Allen's arrest. He secretly left Ireland for France – he is variously said to have escaped disguised in the uniform of the Trinity College yeomanry corps and boarded a ship on the coast between Blackrock and Killiney (Madden), and to have been ‘put into a cask, carried to George's Quay and shipped for France’ (Prendergast). Hickson was arrested and imprisoned (1803–6).
Allen joined Napoleon Bonaparte's newly formed Irish legion as a sous-lieutenant, rising – after showing great valour by leading a mount of a breach at Astorga (1810) and being held captive by Spanish guerillas (1811–12) – to the rank of chef-de-bataillon (lieutenant-colonel) (March 1814). He was one of those who joined Napoleon in 1815 and was lucky to escape capture by the British authorities. In retirement he lived first at Tours (near Gen. William Lawless (qv) and Col. Hugh Ware (qv)) and later at Caen in Normandy. In Paris he became acquainted with Dr Daniel Haliday (d. 1836), a brother of Charles Haliday (qv), as a result of which the latter looked after his financial affairs in Ireland. Secretly John Allen returned very briefly to Ireland (early 1840s) to bring his elderly sisters back to Caen. He died 10 February 1855, apparently unmarried, his property passing to his sisters. Dr Thomas Dromgoole (qv), a leading member of the Catholic Committee who met Allen in France in 1820, considered that he ‘was a man of such firmness of character that he would have been fit to fill the highest situation in Ireland’ (Byrne, Memoirs, iii, 293).