The battalion began its duties on 1 April 1970 with only 200 men to patrol Derry city and a further 300 to cover the rest of the county as opposed to the Ulster Special Constabulary (which the UDR replaced) figures for the previous day of 600 and 1,200 respectively.

[5] Sir Robin Chichester-Clark complained asked in the Parliament of the United Kingdom why one of his constituents was turned down for the force as he was a churchwarden and a local government official.

[6] The reply by Roy Hattersley stated that the vetting team had been instructed to err on the side of caution and that two clergymen had also been refused because the new force was to be "isolated from political and sectarian influence".

The battalion had the largest Tactical Area of Responsibility in the regiment which covered parts of two counties (Londonderry and Antrim) as well as three police divisions 1,600 square miles in total.

He had been Deputy Lord Lieutenant, High Sheriff for County Londonderry and later, Commandant of the City of Derry Ulster Special Constabulary between 1968 and 1970.

[11] Following his retirement after his agreed one year of service he was replaced by the battalion's first regular commanding officer, Lt Col John Lys.

[12] The second in command (2 i/c) of the battalion upon formation was Major George Lapsley, the son of a police inspector, graduate of Magee College, World War II veteran of the Royal Navy (Far Eastern campaign), and officer of the Territorial Army.

Where possible accommodation was sought in army bases and although the old Ulster Special Constabulary platoon huts were vacant and available, to have used those was politically undesirable.

[18] The resulting platoon structure had soldiers from each area regular patrolling territory they were familiar with and where they knew most people from the locality.

By the time E Company took possession of the house and outbuilding they had been converted into a barracks which contained all the facilities expected to be found in UDR company and battalion locations, including a guardroom, armoury, Motor Transport (MT) section, 25 metre indoor rifle range (for .22 Long Rifle .22 calibre only), Officer's Mess, Warrant Officers and Sergeant's Mess, Junior Ranks Bar, snooker room, stores, lecture rooms, offices, operations room, sangars and a pipe range.

It was used in military bases in Northern Ireland for rifle practice when surrounding buildings made it unsafe to establish an open shooting range.

[22] Initially, arms had to be drawn from the North Irish Horse barracks in Ballymoney, which by that time had become B Coy 1 UDR (see also Ulster Defence Regiment#Uniform, armament and equipment).

5 UDR had a number of champion pipers and drummers who, apart from local performances, represented the regiment at the Horse Guards Parade, the Festival of Remembrance in the Royal Albert Hall, London,[9] the Colchester Tattoo, the Queen's Birthday Celebrations in York, an International Air Show at Aldergove and on a tour of the British Army of the Rhine.