British troops deployed into Northern Ireland for the first time 50 years ago after days of rioting in a Catholic heartland that later spread to Belfast and beyond.
Initially planned as a limited intervention to restore order, Operation Banner would last 38 years and become Britain's longest continuous campaign.
Catholic anger over discrimination in voting, housing and jobs first exploded into riots in Londonderry, Northern Ireland's only Catholic majority city, in October 1968.
Tensions boiled over again on August 12, 1969, when stone-throwing Catholics protested an annual Protestant march which skirted their Londonderry ghetto of Bogside.
For three days there were ferocious clashes between police, backed by militant Protestants, and mainly young Catholics.
The police resorted to tear gas and live fire but were unable to stop the barrage of stones, Molotov cocktails and firebombs.
The area resembled a 'battlefield, littered with paving stones, glass debris, projectiles of all kinds and covered with a cloud of tear gas,' an AFP journalist wrote on August 13.
The unrest spread, including to the provincial capital Belfast where the first deaths occurred on August 15.
The Northern Ireland government on August 14 asked British Prime Minister Harold Wilson for help. That afternoon the first British troops rolled into Londonderry.
"Six armoured vehicles of which four belonging to the British army arrived at Waterloo Square in Londonderry where, since 4:00 pm, new violence has broken out," AFP reported.
Numbering 300 by the end of the day, the troops surrounded the Bogside and laid barbed wire to prevent Catholic protesters from entering Protestant neighbourhoods.
Hundreds of more British troops were sent to Northern Ireland the next day, their numbers eventually peaking at almost 30,000.
At first, Londonderry's Catholics welcomed the soldiers and the stand-down of the police, accused of siding with Protestants, with "singing and dancing", AFP reported.
But opinion soon turned and the British troops were also accused of bias.
The following year, the pro-Catholic Provisional Irish Republican Army (IRA) launched a campaign of bombings and shootings against "the forces of the Crown".
IRA militants killed the first British soldier in February 1971, going on to take the lives of more than 760 before the operation was over.
Protestant paramilitary groups reciprocated. The three decades of unrest known as The Troubles drove a wedge between the communities.
British troops were regularly criticised and accused of heavy-handedness.
In the worst such incident, soldiers opened fire on a Catholic civil rights march in Londonderry on January 30, 1972, killing 13 with another person dying later.
The march was illegal and they had orders to make arrests. But, suddenly, 'Troops fired. People screamed, they fled... it was an atmosphere of the apocalypse.'
Three days later a crowd set fire to the British embassy in Dublin.
In March 1972 London suspended the Northern Ireland provincial government and took over direct rule.
Britain would issue a formal state apology for the Bloody Sunday killings in 2010.
The massacre swelled the ranks of the IRA, which extended its campaign to the British mainland with deadly attacks on pubs in 1974.
On August 27, 1979 it assassinated Queen Elizabeth II's cousin, Lord Louis Mountbatten.
Years of effort to find peace finally yielded the breakthrough Good Friday Agreement of April 10, 1998, ending a conflict that had claimed more than 3,500 lives.
It led to a new semi-autonomous Northern Ireland and a power-sharing government between Protestants and Catholics.
In 2005 the IRA disarmed and Britain began scaling down its military presence, formally ending its mission without fanfare just before midnight on July 31, 2007.
Story courtesy: AFP