What is the SAS history?

In 1987 Prime Minister Margaret Thatcher ordered an SAS team into the high-security prison at Peterhead, Scotland. A rebellion by inmates had resulted in one of the prison officers being taken captive. The soldiers were armed with staves and entered the building by way of a skylight. After subduing the inmates with what was called a "hard arrest", which was violent but disciplined and in this case caused no injury, the SAS team freed the prison officer and the operation ended. Some time after the incident, the Prison Service relaxed its zero tolerance attitude to drug use in that prison.