The Black and Tans were a group of recruited constables during the Irish War of Independence (1919-1921). The war was between followers of the British state and guerrilla fighters, also known as the IRA (Irish Republican Army).
So, the Black and Tans were a force of Temporary Constables recruited to assist the Royal Irish Constabulary in maintaining control over the IRA during the Irish War of Independence.
Recruitment began in Great Britain in January 1920 and about 10,000 men enlisted during the conflict.
Due to the heightening tension between British colonial forces and Irish nationals, the police forces were augmented with military veterans from World War I who became known as the Black and Tans.
The Black and Tans were more brutal than ordinary police officers. The majority of them were British, which meant they had less sympathy for the Irish cause, and their military training made them more able to reciprocate violence.
The British administration in Ireland promoted the idea of bolstering the RIC ( Royal Irish Constabulary) with British recruits.
They were to help the overstretched RIC maintain control and suppress the Irish Republican Army (IRA), although they were less well-trained in ordinary policing.
The nickname “Black and Tans” arose from the colours of the improvised uniforms they initially wore, a mixture of dark green RIC (which appeared black) and khaki British Army.
They served in all parts of Ireland, but most were sent to southern and western regions where fighting was heaviest.