For the people like me: https://en.wikipedia.org/wiki/Black_and_Tans
The Black and Tans (Irish: Dúchrónaigh) were constables recruited into the Royal Irish Constabulary (RIC) as reinforcements during the Irish War of Independence.[1][2] Recruitment began in Great Britain in January 1920, and about 10,000 men enlisted during the conflict. The majority were unemployed former British soldiers from England, Scotland and Wales who had fought in the First World War. Some sources count Irish recruits to the RIC from 1920 as "Black and Tans."[3][4][5][6][7]
The Black and Tans had a reputation for brutality; they committed murder, arson and looting and became notorious for reprisal attacks on civilians and civilian property. Their actions further swayed Irish public opinion against British rule and drew condemnation in Britain. The Black and Tans were sometimes confused with the Auxiliary Division, a counterinsurgency unit of the RIC, also recruited during the conflict and made up of former British officers.[8] At the time, "Black and Tans" was sometimes used for both groups.[3][9] Another force, the Ulster Special Constabulary (commonly called the "B-Specials"), was founded in 1920 to reinforce the RIC in Northern Ireland.