The Kilmeena ambush takes place at Kilmeena, County Mayo, on May 19, 1921 during the Irish War of Independence. The ambush ends in defeat for the local West Mayo Irish Republican Army (IRA), with six IRA volunteers killed and seven wounded. Two members of the Royal Irish Constabulary (RIC) and one Black and Tan are also killed in the action.

The IRA in west Mayo is relatively quiet until January 1921, when Michael Kilroy, described as “a puritanical and ascetic blacksmith” takes over command of the Brigade after Thomas Derrig is arrested by the Royal Irish Constabulary. Kilroy forms a relatively large “flying column” of 40 to 50 men to carry out attacks on Crown forces in the area. On May 6 they suffer a reverse at Islandeady, when a police patrol comes upon the IRA men cutting a road. Three volunteers are killed and two captured.

On May 18, 1921, the IRA decides to attack an RIC/Black and Tan convoy at Kilmeena. Two small-unit attacks are made on the RIC barracks in Newport and Westport to try to draw the police out of their well-defended barracks. One RIC man dies in these attacks.

At 3:00 AM the next day, May 19, the column of 41 IRA men take up position close to Knocknabola Bridge. The British convoy, traveling from Newport to Westport, consists of two Crossley lorries and one Ford touring car and a total of about thirty men. The convoy does not arrive until 3:00 PM and its arrival sparks a two-hour fire-fight. In the battle, one RIC man is wounded and later dies. The British regroup around the house of the parish priest, Father Conroy, and launch a counterattack.

Four IRA volunteers are killed. They are Seamus Mc Evilly, Thomas O’Donnell, Patrick Staunton and Sean Collins. Paddy Jordan of the Castlebar battalion is injured and dies later at Bricens Hospital in Dublin. Seven more IRA men are wounded.

The remainder of the column, carrying their wounded, flee over the mountains to Skerdagh, where they have safe houses. However, the police track them there and, in another exchange of fire, another IRA man is killed, Jim Brown from Newport, along with one RIC Constable and a Black and Tan.

The Black and Tans throw the dead and wounded IRA men onto the street outside the RIC barracks in nearby Westport, causing widespread revulsion among the local people and local police. The Marquis of Sligo, no friend of the republican guerrillas, visits the barracks to complain of their treatment of enemy dead. At the funerals of those killed, in Castlebar, the authorities allow only close family to attend and forbid the draping of the Irish tricolour over the coffins.

The local IRA blames their defeat in the ambush on the failure of an IRA unit from Westport to show up in time.

Kilroy’s column manages to get some revenge for the setback at Kilmeena the following month in an action at Carrowkennedy on June 3, where they kill eight policemen and capture sixteen.