In the Republic of Ireland, economic prosperity had made most citizens happy with life and indifferent to Northern Ireland and the issue of reunification. However, it soon began to look as if the Northern Ireland government was suppressing a valid Civil Rights movement which was now collapsing into Civil War. On August 13th, the Irish Taoiseach Jack Lynch said that the Irish government would not "stand by and see innocent people injured". Some Unionists thought this was a threat to invade Northern Ireland to protect the Catholic population. It is also thought that the Irish began placing troops near the border at this time.

The UK government realised in August that Northern Ireland was about to collapse into anarchy because the RUC was simply not large enough to maintain order. So, on 15 August, the UK Prime Minister, Harold Wilson, ordered the British Army into Belfast and Derry to support the RUC. (The Army is still in Northern Ireland today.) Four days later he also ordered the Stormont government to establish better community relations, introduce 'one man one vote', disband the B-specials, and disarm and restructure the RUC. With all their demands now unexpectedly met, the official Civil Rights campaign shut down.

However, this was not the end of the story. The violence that had erupted, directed mainly towards the Catholic community, had prompted many people there to rekindle their old desire for a united Ireland. In 1969 a fierce debate began within the ranks of the IRA. Some members supported the non-violent strategy. However many others accused the leadership of 'going soft' on the aim of a united Ireland and pointed to the new presence of the British Army in Northern Ireland. This militant group split off in 1970, formed the 'Provisional IRA' and began a ruthless bombing campaign in Northern Ireland, (and sometimes on mainland Britain) designed to destroy the economy and force the British to withdraw. The Provisional IRA almost certainly received money and arms from members of the Irish Government to start their campaign, although the Taoiseach sacked the members involved in the scandal. The Provisionals also targetted policemen and became increasingly involved in civilian demonstrations and riots. 25 people were killed in 1970 and 174 in 1971. The loyalist UVF began to use violence to 'protect the Protestant community' from the Provisional IRA and also launched their own offensives against Catholics and against the Irish Republic.

By mid 1970, the Northern Ireland government realised that the Provisional IRA was rapidly recruiting and would soon have the ability to fight a significant war in Northern Ireland. They also realised that, if they struck now, the army might have a chance to check this growth. So on an evening in late July 1970 the army imposed a curfew on the Catholic Falls Road in west Belfast and began storming homes and searching for arms. However the searches uncovered arms in only 5% of the houses searched; much fewer than had been anticipated. The searches were so violent that the nett effect was to increase support for the IRA and speed up their recruitment.

In April 1970, Ian Paisley won a seat at Stormont which served only to underline the split within Unionism between the moderates and the extremists. At the same time, the Alliance Party was formed in an attempt to bring about reconciliation between the two sides. And in August 1970, a group of socialist nationalist politicians formed the Social Democratic and Labour Party (SDLP), a party with no links to terrorism, which soon became the main voice of the Nationalist community in Northern Ireland.

By August 1971, the army and RUC had a good idea who the main members of the terrorist organisations were. So they decided to introduce Internment (to arrest and hold people without evidence) to take them off the streets and hopefully prevent further murders. Within six months, 2357 people (mainly from the Nationalsit community although about 10% of the final total were Loyalists), 1600 of whom were subsequently released wthout charge. However, it was badly organised. Many innocent people were detained and most of the leaders of the terrorist organisations slipped through the net. Despite its good intentions, Internment served only to increase support for terrorism yet again. Rioting against Internment began. In January 1972, a huge anti-Internment rally was organised in Derry. Although the march itself passed off peacefully, rioting broke out as it ended. Believing themselves to be under an armed IRA attack, the army opened fire on the protestors. 14 people were killed, none of whom were subsequently found to have been armed. Forensic evidence also proved that none of them had fired a weapon at any time during the day. The event became known as 'Bloody Sunday'. The killings (and the subsequent Widgery report which did not recommend charging the soldiers) outraged the nationalist community and fresh rioting began and the IRA strepped up its bombing campaign.

The Northern Ireland Prime Minister, Brian Faulkner, faced with a near civil war, demanded that the UK government permit them to re-arm the RUC and re-establish the B-specials. Instead the British Prime Minister, Edward Heath, ordered Stormont to relinquish control of the police in Northern Ireland and place them under direct London control. Faulkner was outraged and blankly refused, defying the government. Heath then took the decision, in March 1972, to suspend the Stormont government and rule Northern Ireland directly from London pending the introduction of a new system of government. In the mean time, the Northern Ireland Office (NIO) was established in London to govern the province. The UK government also abolished Internment and gave all Northern Ireland people the right to a fair trial.

Most in the Unionist community were astounded, angry and outraged at what they called a 'betrayal of Ulster'. The terrorist group, the Ulster Defence Association (UDA) was formed to 'protect the Protestant people'. While many Protestants supported the terrorists, many more would have nothing to do with them. Many nationalists were pleased that Stormont had finally fallen, but continued the Civil Rights campaign. Although the Irish government welcomed the move and pleaded with the IRA to call a ceasefire, the IRA regarded London rule as worse than Belfast rule and stepped up their campaign of murders and bombings. They announced that they would rid Ireland of the British even if they had "to demolish Belfast brick-by-brick". In 1972, 467 people were murdered in Northern Ireland. The situation got so bad that the UK government even agreed to negotiate with the IRA in 1972. The IRA called a truce during the meetings. However the IRA demands - giving Northern Ireland to the Irish Republic - were out of the question to the UK government and they refused. The IRA response was to detonate 26 no-warning car bombs within 40 minutes in Belfast on 21 July 1972. 11 people were killed and 130 injured. The day is now known as 'Bloody Friday'.