The disclosure in Sir Edward Heath's autobiography The Course of My Life that the government had contemplated strikes from the air and sea to put down the IRA - with the risk of civilian casualties - will horrify the nationalist leaders now engaged in the peace process.
The cabinet papers covering the period have yet to be released under the 30-year Whitehall secrecy rule, but Sir Edward says the crisis came close to open warfare after Bloody Sunday in January 1972, when 14 people on a march in Londonderry were killed by British forces.
After months of growing tension caused by Bloody Sunday, Operation Motorman was launched in July 1972 by the RUC to retake the no-go areas in the nationalist Bogside and Creggan, which were effectively being run by the IRA. Sir Edward described the night before as "one of the worst of my life.
"We were taking a considerable risk. All of us involved in the decision ... knew that the Provisionals were capable of organising fierce and bloody resistance to the forces of law and order.
"We had the RAF on standby and the navy offshore below the horizon."
Two civilians were killed but open conflict was avoided. Speaking to The Independent, Sir Edward confirmed the British forces were not stationed to carry out an evacuation. "We were taking over the whole of the Bogside. They would just have to intervene in any battle that was going on," he said.Reuse content