The movement for more Irish self determination had turned into a full out revolutionary movement by 1919. The British Empire was losing control over Ireland and by early 1920 was in a full out guerrilla war against the Irish Republican Army (IRA). To regain control more police forces were recruited with wide ranging authorities - and a lack of actual police training. With their mismatched equipment made from war supplies, they soon got the nickname "Black and Tans".
