The UDR: What was the Army's Ulster Defence Regiment? - BBC News
The UDR only operated in Northern Ireland for 22 years but its legacy has been controversial.
The Ulster Defence Regiment (UDR) was a British Army unit that operated in Northern Ireland for 22 years from 1970.

It was mainly involved in patrol and checkpoint duties.

About 250 serving or former members were killed during the Troubles by the IRA and other republican groups.

Many of the victims were part-time members of the regiment, murdered while off-duty either at home or at work.

The UDR was overwhelmingly Protestant in make-up.

UDR troops being inspected at Ballykinler in 1992

In its early days, it had up to 18% Catholic membership but suffered an early image problem with nationalists, who saw it as absorbing too many former B Specials, a largely Protestant reserve police force.

About 40,000 people served in its ranks over its lifetime.

A minority of its personnel - soldiers by day and paramilitaries by night - were directly involved in sectarian murders.

Others provided loyalist groups with weapons and intelligence.

Documents uncovered in the National Archives have revealed the government was aware of collusion from 1973.

State papers that emerged in 2016 also indicated that the public image of the UDR was widely discussed by the government in the 1970s and 1980s, with arguments being made for a tougher vetting procedure.