In the face of continuing violence and under pressure from members of his own party to do something that worked, Prime Minister Brian Faulkner decided to introduce internment to deal with those believed to be involved in terrorism.
On 9th August 1971 Operation Demetrius started and 452 men were arrested.
However those arrested were, by and large, the wrong people.
The information that was used was out of date; those interned were mainly members of the Official IRA (OIRA), ordinary nationalists or civil rights supporters - and not the Provisional IRA.
On top of that no loyalists were among the 452 men arrested even though the loyalist paramilitaries were also involved in killings and bombings.
The first Loyalists were not interned until February 1973.