When were the Northern Ireland Troubles, what happened in Belfast and what is the Good Friday Agreement?

TWENTY years ago a historic peace agreement signalled the end of three decades of sectarian conflict in Northern Ireland.

But what were the Troubles and what is the Good Friday agreement? Here's the lowdown on the years of bloody violence.

When were The Troubles?

The Troubles describe a 30-year period between the late 60s and early 90s, when sectarian violence in Northern Ireland caused the deaths of thousands of civilians and security personnel.

Historians tend to place the beginning of the Troubles with the 1968 civil rights movement, which demanded an end to Unionist-dominated rule from the devolved Northern Ireland government at Stormont.

Marches, protests, civil disobedience and increasing violence led to the British government's decision in 1969 to deploy troops to the streets, especially in Belfast and Londonderry.

In 1971, the government introduced its policy of internment, locking up terror suspects without trial.

By the following year, the situation had deteriorated.

On Bloody Sunday, 13 unarmed people were shot and killed by the British Army during a civil rights march in Londonderry.

The British government then suspended Stormont's rule and imposed direct rule from London.

The Provisional IRA, an offshoot that would eventually overtake the Official IRA, saw a surge in membership and its bombing and assassination campaign against security forces and Protestants picked up.

Meanwhile, pro-British paramilitary groups like the UDA (Ulster Defence Association) and UVF (Ulster Volunteer Force) committed to violence against Catholics and the IRA to prevent a united Ireland.

Bombings and shootings continued uninterrupted for the next thirty years, with multiple massacres leaving scores dead.

The worst atrocity was the IRA's Omagh Bombing in 1998, which left 29 innocent people dead including six teenagers, six children and a woman pregnant with twins.

In all, it is estimated that between 3,500 and 4,000 people died as a direct result of Troubles violence. At least 50,000 were maimed or badly injured.

In a country that at that time had barely over a million people, this level of violence was crippling.

What is the Good Friday agreement?

The Troubles came to an end in 1998 with the signing of the Good Friday Agreement, also known as the Belfast Agreement.

This historic treaty on April 10 put in place a cross-community power-sharing government in Stormont and a disarmament programme.

Covering two different documents - a multi-party agreement and a British-Irish agreement - the agreement was backed by voters in a referendum in May 1998.

Direct London rule came to an end when the British-Irish Agreement came into force on December 2, 1999.

The multi-party agreement committed Sinn Féin and the Progressive Unionist Party to "use any influence they have" to bring about the decommissioning of all paramilitary arms within two years of the referendums approving the agreement.

Has the treaty worked?

The peace process has not been all plain sailing.

The new executive model in Stormont proved problematic, and distrust between the parties led to the assembly being suspended several times.

From 2002 until 8 May 2007, when the St Andrews Agreement was signed, Northern Ireland was once again directly ruled from Westminster.

Before stepping down Tony Blair managed to win over Ian Paisley, despite previously saying the idea of the DUP man agreeing to a deal was “pie in the sky”.

The new accord made ministers more accountable to the executive and the assembly, while the first minister and deputy first minister would now be nominated by their parties rather than elected.

Conflict arose again in 2017, with the DUP and Sinn Fein unable to come to an agreement on power-sharing.

Without a devolved executive, the British government moved to impose a budget directly on Northern Ireland.

Brexit has also raised questions about peace in Northern Ireland.

There have been fierce debates over the prospect of a post-Brexit "hard border", which could ignite sectarian tensions if imposed.

Sinn Fein and the unionists are touting a  as an alternative means to remain in the EU, something the DUP vehemently opposes.

George Mitchell, who as US Special Envoy for Northern Ireland chaired the talks that led to the historic agreement 20 years ago, has warned that a perfect storm of direct rule and a hard border could lead to “serious trouble” and a return to the violence of the 1970s and 1980s.

What was Belfast's Bloody Sunday?

The Ballymurphy Massacre was a series of events that took place between August 9 and 11, 1971.

It saw British soldiers from the 1st Battalion, Parachute Regiment kill eleven civilians in Ballymurphy in Belfast, Northern Ireland.

The killings became known as Belfast’s “Bloody Sunday”.

On August 9, more than 600 British soldiers from the 1st Battalion, Parachute Regiment entered the area and began raiding homes and rounding up men of all ages without reason.

The raids came as part of Operation Demetrius and were designed to arrest and intern anyone suspected of being a member of the Provisional Irish Republican Army (IRA).

Soldiers carried out early morning raids at around 5am, kicking down doors and dragging unsuspecting civilians from their beds.

Members of the 1st Battalion Parachute Regiment claim that as they entered the Ballymurphy area, they were shot at by republicans and were forced to return fire.

However, there is no photographic or video evidence, or accounts from journalists that could prove exactly what happened.

Statements provided by the troops claiming they fired in retaliation have always been angrily rejected by the victims’ families who maintain that the killings were unprovoked.

A new inquest is due to open in September 2018, in the hope of establishing precisely what happened.

Ahead of this, a Channel 4 documentary, Massacre at Ballymurphy, aired on Saturday, September 8, 2018, at 9pm, revisiting the fatal gun battle that saw eleven citizens fatally shot.

Timeline - how the Troubles unfolded

• August 1969: The British government deploys troops in Northern Ireland in a "limited operation" to restore law and order, following three days of violence in the Catholic Bogside area of Londonderry
• February 1971: Gunner Robert Curtis becomes the first British soldier to die when he is shot dead by the IRA
• January 30, 1972: On Bloody Sunday, the British Army shot and killed thirteen unarmed people during a civil rights march in Londonderry
• March 1972: The Stormont Government is dissolved and direct rule imposed by Westminster
• October 1974: Pubs are bombed in Guildford as the IRA expands its campaign to mainland Britain. A month later, there are more pub bombings in Birmingham, killing 21 people
• July 1976: British Ambassador to Ireland Christopher Ewart Biggs is murdered by a car bomb in Dublin
• October 1984: A bomb explodes at the Grand Hotel in Brighton, where Margaret Thatcher PM was staying during the Conservative Party conference
• November 1985: Margaret Thatcher and Garret FitzGerald, the Irish Taoiseach, sign the Anglo-Irish Agreement, paving the way for co-operation between the two governments.
• November 1987: 11 civilians are killed by a Provisional IRA bomb at a Remembrance Day service in Enniskillen
• April 1998: The Good Friday Agreement is signed, hailing the end of the Troubles

Will Brexit affect the Good Friday Agreement?

There are fears Britain leaving the EU could "re-ignite" the conflict in Northern Ireland.

Experts have claimed north-south relations, the peace process, border controls, racism and socio-economic rights will all be negatively affected by Brexit.

But former first minister David Trimble said there was no serious threat of post-Brexit violence in Northern Ireland.

Although he said the agreement would be breached if Northern Ireland was part of a different trade regime than the rest of the UK.

DUP leader Arlene Foster also spoke out in October 2018 - saying the Good Friday Agreement is not "sacrosanct" and the landmark peace treaty could be altered to accommodate a Brexit deal.

She said the agreement could "evolve" in the EU context.

The UK and the EU both want to avoid a "hard border" with Michel Barnier saying on September 18, 2018, the EU is "ready to improve" its offer on the Irish border.

A hard border would mean border checks being reintroduced on the border between Ireland and Northern Ireland.

Currently the border is open with no checks on goods or people, with Ireland and the UK in a "common travel area" of passport-free movement.