Denis “Dinny” Lacey, Irish Republican Army (IRA) officer during the Irish War of Independence and anti-Treaty IRA officer during the Irish Civil War, dies at Glen of Aherlow, County Tipperary on February 18, 1923.

Lacey is born on May 31, 1889 in the village of Attybrick, near Annacarty, County Tipperary. He joins the Irish Volunteers in 1913 and is sworn into the secretive Irish Republican Brotherhood (IRB) in 1914. He is introduced to the IRB by Seán Treacy. During the War of Independence (1919–1921) he is selected to command an IRA flying column of the 3rd Tipperary Brigade, in September 1920. The flying column mounts two successful ambushes of British forces – killing six British soldiers at Thomastown near Golden, and four Royal Irish Constabulary (RIC) men at Lisnagaul in the Glen of Aherlow.

In April 1921, following another ambush of British troops near Clogheen, he captures RIC inspector Gilbert Potter, whom he later executes in reprisal of the British hanging of republican prisoners.

In December 1921, Lacey’s unit splits over the Anglo-Irish Treaty. He opposes the Treaty and most of his men follow suit. He takes over command of the 3rd Tipperary Brigade as Séamus Robinson is appointed to commanded the anti-Treaty IRA’s Second Southern Division. In the ensuing civil war (June 1922-May 1923), he organises guerrilla activity in the Tipperary area against Pro-Treaty Irish Free State forces.

Denis Lacey is killed in an action against Free State troops at Ballydavid, near Bansha in the Glen of Aherlow on February 18, 1923. He is 33 years old at the time of his death. Over 1,000 Free State troops drawn from Cahir, Cashel, Clonmel, and Tipperary, under the command of General John T. Prout, with the intention of breaking up Lacey’s guerrilla unit, converge on the Glen where he and four other men from his column are billeted. Lacey and one of his men are killed and others are captured. Two National Army soldiers are killed in the action.

A memorial in Annacarty commemorates Lacey’s war service and subsequent death in action.