The British army will officially end its peacekeeping role in Northern Ireland on Tuesday after a 38-year presence that has involved more than 300,000 personnel and cost the lives of more than 750 soldiers.

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A British army soldier from the Royal Regiment of Scotland stands on guard inside Palace Barracks in Belfast, Northern Ireland, on Tuesday. ((Peter Morrison/Associated Press))

Since the Good Friday Agreement nine years ago, the army has discreetly lessened its numbers in the mission and slowly dismantled its bases and observation towers.

As of midnight Tuesday, the force will see its ranks in the province dwindle to 5,000 soldiers, down from the 27,000 deployed at the height of the sectarian conflict that became known as "the Troubles."

"It's a huge psychological step," the Independent's David McKittrick told CBC News on Tuesday in an interview from Belfast.

"Everyone here has grown up with heavily armed troops and armoured vehicles in the streets. So the idea that we can get by without them is a huge one."

Although full reconciliationbetweenCatholics and Protestants is still "decades away" from being realized,both sidesare welcoming the army'shistoric pullout,he noted.

"For once, there aren't two different reactions from Protestants and Catholics," McKittrick said. "Although we have many problems, the sense is things are going to gradually get better."

Conor Murphy, Northern Ireland's minister for regional development and a member of the legislative assembly for Sinn Fein, said that in his constituency, the army was always viewed as an occupying force and their presence was resented.

"But I think regardless whether people welcomed them here or felt they were necessary here or not, I think there is a sense their departure here today marks another milestone in our own peace process here," he told CBC News.

Some 3,700 killed in decades-longconflict

In August 1969, British troops with bayonets fixed marched into a Northern Ireland divided along sectarian lines, aimingto prevent the outbreak of civil war under a mission dubbed "Operation Banner."

Most of the soldiers and their commanders believed they would only be in Northern Ireland for a few weeks. But years of violencesaw about 3,700 killed —including 763 Britishsoldiers and 309 people killed by British troops during the longest continuous campaign in the army's history.

At first, the troops' role was to keep the peace between Catholics and Protestants after nightly rioting had exhausted the local police and panicked Northern Ireland's Unionistgovernment into calling on London to send the troops.

Initially, the mission appeared to be going well. Many Catholics were happy to see the army, believing their presence would protect them against Protestant rioters. Grainy television images from the early days showed a Catholic woman pressing a British soldier to accept a piece of cake.

But as the mission continued, such sentiments among Catholics soon dissipated and were replaced by resentment,distrustandhatred as Britain allowedtheProtestant government to wield control over how British forces were used.

A newly formed"Provisional" IRA began launching attacks against police and, eventually, the army, killing its first soldier in February 1971. Protestant leaders used the army to impose internment without trial almost exclusively against IRA suspects in Catholic areas.

Soldiers' casualty rate in 1970s higher than in Iraq, Afghanistan

But perhaps the army's presence in Northern Ireland is best known for the events ofJanuary 30, 1972 —known as Bloody Sunday—a day in which British paratroopers shot and killed13 unarmed Catholic demonstrators in Londonderry during a civil rights march.

A second inquirywasestablished in 1998 by British Prime Minister Tony Blair to find the truth behind the incident. Presided by three judges, including former New Brunswick Chief Justice William Hoyt,the Bloody Sundayinquiry heard testimony from more than 900 witnesses and has yet to present its final findings.

The bloodletting would continue for decades, with bombings and shootings spreading to the streets of major British cities, including London.

Retiredcolonel Mike Dewar, a security analyst who served several tours in Northern Ireland, called the death toll in the early 1970s "horrific — a much higher casualty rate than what we have suffered in Iraq or Afghanistan."

Intelligence agents eventually built a detailed picture of the IRA based on surveillance and informers. Undercover army squads wiped out several IRA units in one-sided gun battles in the 1980s and early 1990s, a brutal strategy that Dewar credits with spurring the IRA's ceasefire.

"The IRA were clearly infiltrated. The pressure became unbearable for the IRA," Dewar said.

In 1997, after intense negotiationsbrokered by Blair and IrishPrimeMinisterBertie Ahern, a peace process took hold that eventually brought the two sides together into a power-sharing agreement.

The IRAformally announcedan end toits armed campaign in July 2005 and ordered all its units to place their weapons into arms dumps and cease all activities.

With files from the Associated Press