In March 1971, Chichester-Clark resigned and was replaced by Brian Faulkner. Unrest in the province had achieved a new level, prompting the new prime minister to reintroduce internment - detention of suspects without trial - on 9 August 1971.
It was a disaster, both in its failure to capture any significant members of the PIRA and in its focus on nationalist - rather than loyalist - suspects.
'The events surrounding 'Bloody Sunday' remain the subject of intense controversy. '
The reaction was predictable, even if the ferocity and extent of the violence wasn't. Deaths in the final months of 1971 exceeded 150. It was sadly still far from the bloodiest year of the Troubles.
Policing the province was fast becoming an impossible task, and as a result the British Army had adopted increasingly aggressive policies on the ground.
Then on 30 January 1972, the army deployed the Parachute Regiment to suppress rioting at a civil rights march in Derry. Thirteen demonstrators were shot and killed by troops, with another dying later of wounds.
The events surrounding 'Bloody Sunday' remain the subject of intense controversy. But as a result of the killings, new recruits swelled the ranks of the IRA and yet more British troops were deployed to the province to try and contain the ever-rising tide of violence.
Protestants also expressed their growing discontent with the formation of the Ulster Vanguard, an umbrella organisation for loyalist groups that was able to attract tens of thousands to public meetings.
The British government, led by Prime Minister Edward Heath, decided to act, removing control of security from the government of Northern Ireland and appointing a secretary of state for the province.
The Stormont government resigned en masse in protest at this perceived assault on their powers. Heath responded by immediately introducing what would become known as 'direct rule' - government of Northern Ireland from Westminster.