Lacey, Denis (‘Dinny’) (1890–1923), republican soldier, was born at Attybrick, Annacarty, Co. Tipperary. Educated at the local national school, Lacey was a keen Gaelic League activist and as a teenager joined the IRB, subsequently becoming one of the first members of the Irish Volunteers in Tipperary town. After the 1916 rising he aided Seán Treacy (qv) and Dan Breen (qv) in the reorganisation of the Irish Volunteers in Tipperary and became a member of the Third Tipperary Brigade of the IRA, supervising the completion of new munitions factories in Shrough and Knockharding during the war of independence. After Treacy's death in October 1920 Lacey became OC of the flying column formed by Treacy to operate throughout south Munster, and led significant actions against British soldiers at Thomastown in October 1920 and against the Black and Tans and RIC at Inches Cross, Lisnagaul, in the Glen of Aherlow the following month. Lacey, described by Dan Breen as an absolute dreamer and idealist who would not countenance compromise, strongly rejected the Anglo–Irish treaty and persuaded many young men, sometimes through intimidation and pressure, into the anti-treaty ranks in the Tipperary district.
During the prologue to the civil war he led the notorious raid on Clonmel barracks (February 1922) during which 300 rifles, 200,000 rounds of ammunition, bombs, and twelve armoured cars were seized by the republicans. Often demonstrating reckless bravery, Lacey's no. 3 Brigade was referred to as ‘a little republic of its own’ (Hopkinson, 167), and early during the civil war he was said not to have been on speaking terms with the divisional OC, Séamus Robinson (qv), from whom he refused to take orders. Lacey had been in charge of flying columns during the attempted defence of Waterford city during the civil war, but retreated to Carrick-on-Suir, which he used as his base, and there were disagreements between himself and Robinson over the burning of creameries. Failure to cooperate continued, and between September 1922 and January 1923 south Tipperary represented a disappointing failure for militant republicans, with few military operations undertaken, and Lacey operating largely on his own. Mindful of his strong reputation as a fighting man, a Free State army report concluded that ‘Lacey was the toughest leader which [sic] could be found in any part of Ireland’ (Hopkinson, 238), though it went on to insist that the army had disorganised his flying columns and made them scatter into areas where they were vulnerable to capture.
A deeply religious man even when on the run, Lacey took a hard line against looting by his men, issued frequent threats against public bodies, and reacted strongly to Free State executions. In January 1923, after the threatened execution of the captured Liam Deasy (qv), he ordered the arrest of five farmers who were brothers of the Free State army's ex-IRA commanders, and threatened to execute them in the event of Deasy's execution. Free State officers responded by threatening to kill every male member of the Lacey family in south Tipperary. Lacey was shot dead by Free State soldiers on 18 February 1923 while trying to escape from a house in Ballydavid in the Glen of Aherlow. It was rumoured that his presence there was due to an invitation he had received to a meeting at Rossadrehid from neutral ex-officers of the IRA to discuss peace proposals. He was buried at St Michael's cemetery, Tipperary.