On Tuesday, 21 January 1919, between the hours of 12:30 pm and 1 pm, two Royal Irish Constabulary (RIC) constables were ambushed near Tipperary town and shot dead. This attack is generally regarded as the start of the horrific and bloody guerrilla war which became known as the Anglo-Irish War.

Constables James McDonnell and Patrick O'Connell (both Irish born Catholics), had been walking with loaded rifles escorting a horse drawn cart containing a load of gelignite from Tipperary Military Barracks for blasting purpose at Soloheadbeg Quarry (located 3 miles from Tipperary). Constable McDonnell, who was about 50 years was from Belmullet, County Mayo. He was a widower with four children. Constable O'Connell, from Coachford, County Cork, was about 30 years and unmarried. According to the page 1 of The Cork Examiner 21 January, 1919 and Robert Kee author of The Green Flag" (London 1972), p.632, both constables were very popular policemen within the community.

The driver of the cart was a James Godfrey, who was accompanied by Patrick Flynn, a County Council employee. A group of masked men of the I.R.A.'s 3rd Tipperary Brigade, which included Dan Breen, Séan Hogan, Séamus Robbinson and Séan Treacy, jumped over the roadside fence near the quarry and shouted "hands up". Dan Breen claims in his book "My fight for Irish Freedom" (Anvil Books Dublin 1928) that the constables raised their rifles in preparation and that they were forced to kill the two constables. After loading up the constables' rifles and ammunition, Hogan drove the cart away with Treacy, Breen and the explosives away in the direction of the quarry while the others headed towards Coffey's forge. Witnesses later saw the cart been driven furiously towards Dundrum, County Tipperary, by two masked men with a third in the back. The horse and cart minus the explosives were later found abandoned at Allen Creamery near Dundrum, by District Inspector Poer O'Shee of Clonmel and Sergeant Horgan of Tipperary.

The following day Martial Law was imposed and on page 1 of the Cork Examiner 21 January, 1919, the following communiqué was published; "In view of the murder of police constables in Tipperary yesterday, the Irish Government has determined to proclaim the district a military area immediately - Press Censor, Ireland". The British Government offered a reward of £1,000 and wanted posters containing photographs of Dan Breen were posted outside every police barracks in the country (Click here to see the RUC Museum's copy of the wanted poster - external link). Descriptions of Breen, Hogan, Robbinson and Treacy were given in the RIC's "Hue and Cry".

Hogan was eventually arrested in May 1919 and sent to Cork jail to await trial. On 13 May 1919, while Hogan was being escorted from Thurles RIC Barracks to the Cork city's jail by four armed policemen, a group of Hogan's comrades boarded the train at Knocklong Railway Station and attacked the police escort. Hogan was freed but Sergeant Peter Wallace and Constable Michael Enright of the Royal Irish Constabulary were shot dead and Breen and Treacy were seriously wounded.

Breen and Treacy recovered from their wounds but Séan Treacy was later shot dead on 15 October 1920, in a gun fight in Talbot Street, Dublin. Dan Breen survived both the Anglo-Irish War and Irish Civil War and became a TD (member of the Irish Parliament - Dáil Éireann) for North Tipperary.