It was founded in July 1920 by Major-General Henry Hugh Tudor and made up of former British Army officers, most of whom came from Great Britain and had fought in the First World War.

Its role was to conduct counter-insurgency operations against the Irish Republican Army (IRA), acting mainly as a mobile striking and raiding force.

[2] During a Cabinet meeting on 11 May 1920, the Secretary of State for War, Winston Churchill, suggested the formation of a "Special Emergency Gendarmerie, which would become a branch of the Royal Irish Constabulary".

Macready's committee rejected Churchill's proposal, but it was revived two months later, in July, by the Police Adviser to the Dublin Castle administration in Ireland, Major-General H H Tudor.

[4] In a memo dated 6 July 1920, Tudor justified the scheme on the grounds that it would take too long to reinforce the Royal Irish Constabulary (RIC) with ordinary recruits.

At that time, one of high unemployment, a London advertisement for ex-officers to manage coffee stalls at two pounds ten shillings a week received five thousand applicants.

Enlisted men who had been commissioned as officers during the war often found it difficult to adjust to their loss of status and pay in civilian life, and some historians have concluded that the Auxiliary Division recruited large numbers of these "temporary gentlemen".

[7] Piaras Beaslaí, a former senior member of the IRA who supported the Anglo-Irish Treaty, while paying tribute to the bravery of the Auxiliaries, noted that the force was not composed exclusively of ex-officers but contained "criminal elements", some of whom robbed people (including a number of Unionists) on the streets of Dublin and in their homes.

Divided into companies (eventually fifteen of them), each about one hundred strong, heavily armed and highly mobile, they operated in ten counties, mostly in the south and west, where Irish Republican Army (IRA) activity was greatest.

On 19 March 1921, the 3rd Cork Brigade of the IRA defeated a large scale attempt by the British Army & Auxiliary Division to encircle and trap them at Crossbarry.

[citation needed] Many of the Division's Temporary Cadets did not cope well with the frustrations of counterinsurgency: hurriedly recruited, poorly trained, and with an ill-defined role, they soon gained a reputation for drunkenness, lack of discipline, and brutality worse than that of the Black and Tans.

One British officer, who served as adjutant for the 2nd Battalion, Cameron Highlanders, wrote in his memoirs that the Auxiliaries "were totally undisciplined by our regimental standards".

On the evening of Bloody Sunday, for example, Dick McKee and Peadar Clancy were killed by their Auxiliary captors under very suspicious circumstances: the official explanation, that the two insurgents tried to escape, is widely disbelieved.

The British Government at first claimed the citizens were responsible for the arson, but a military court of inquiry known as the Strickland Report later found that the fires had been started by the Auxiliaries.

[19] Concerned that parallels would be made between this case and the killing of Francis Sheehy-Skeffington, the British Cabinet directed that Hart should be examined by at least two medical experts, a highly unusual intervention.

[20] Although Hamar Greenwood announced to the House of Commons that he would be detained at His Majesty's pleasure, Hart was briefly held at Broadmoor Criminal Lunatic Asylum before release the following year.

Two hours later, constables of the Dublin Metropolitan Police found the two men lying shot in Drumcondra: Kennedy was dead, and Murphy was dying.