On 6 August 1914, less than 48 hours after Britain's declaration of war, Parliament sanctioned an increase of 500,000 men for the Regular British Army, and the newly appointed Secretary of State for War, Earl Kitchener of Khartoum issued his famous call to arms: 'Your King and Country Need You', urging the first 100,000 volunteers to come forward.

Later in the year it became part of Kitchener's Fifth New Army (K5) and was officially numbered as the 12th (Service) Battalion, Gloucestershire Regiment (Bristol), but the subtitle was usually rendered as 'Bristol's Own'.

The recruiting committee encouraged 'mercantile and professional' men to apply, both through reasons of social exclusiveness and with a view to Kitchener's directive that workers in vital industries could not be spared.

But in late September the recruiting committee persuaded the War Office to buy up the site of the abandoned Bristol International Exhibition in Greville Smyth Park, the buildings of which were converted into barracks by the Royal Engineers and Army Service Corps.

Previously, most of the shooting had been on miniature ranges with .22 ammunition; now the men began weekly musketry courses (12th Gloucesters at Whitburn, County Durham) although many of the rifles were worn and defective.

In August, 32 Division gathered on Salisbury Plain to begin final battle training, with 12th Gloucesters in camp at Codford.

He was succeeded in command by Lt-Col Martin Archer-Shee, a former Regular Army officer who was now Member of Parliament for Finsbury Central.

[23][24] Steel helmets began to be issued to British troops early in 1916, but there were great shortages: Lt-Col Archer-Shee used his position as an MP and own observations in the trenches to ask embarrassing questions of the Under-Secretary of State for War.

Ballard, was wounded on 20 July, Lt-Col Archer-Shee took temporary command until Brig-Gen Lord Esme Gordon-Lennox arrived to take over.

[22][25][26] From 23 to 26 July the battalion was in the front line and was heavily shelled, with high explosive, shrapnel and gas, suffering many casualties.

12th Gloucesters put in two companies on the left of the brigade after a half-hour bombardment, and they successfully advanced the line some 500 yards (460 m) beyond Duke Street.

Although the battalion had been told that it would not have to go back into the line, it received a draft of 116 reinforcements and was given a role in 95th Brigade's next attack, the Battle of Morval on 25 September.

[35] After the end of the Somme offensive, the battalion continued to do duty in the appalling trenches in the area, alternating with tents in devastated Mametz Wood.

12th Gloucesters repulsed the first at 03.45 (which may have been an unplanned clash as the German storm troops moved into position) but the battalion was overwhelmed by the second attack at 05.45, which completely broke through the British lines and recaptured Fresnoy.

[22][38][39][40] The battered battalions were slowly built up to strength and trained hard, but 12th Gloucesters did not see major action again until the latter stages of the Third Ypres Offensive.

In preparation for the next attack (the Battle of Poelcappelle on 9 October), 12th Gloucesters was in Sanctuary Wood, where it was under observation and artillery fire from the enemy and movement was restricted to duckboard tracks.

On 8 October the battalion was split, with two companies providing carrying parties and the other two in the support line behind 1st Bn Cheshire Regiment.

When the attack was delivered, the companies in Sanctuary Wood provided carrying and burial parties, while the two in the support line were pinned by artillery and could not be relieved until 10/11 October.

[22][42][43][44] While 5th Division continued to attack (the Second Battle of Passchendaele), 12th Gloucesters remained out of the line after Poelcapelle, resting, absorbing a few reinforcements, and training.

At the end of October Lt-Col Rawson left the battalion for a six-month tour of duty in the UK and the second-in-command, Maj H.A.

It took all its objectives by 09.30, and pushed patrols up to the Plate Becq river, though a handful of German machine guns had caused 164 casualties, of whom 45 died.

Once the second objective had been taken, 12th Gloucesters took over and, despite having lost the barrage, advanced over a mile of open country with some of 1st East Surreys and just reached the Arras–Albert railway before meeting stronger opposition.

Next day the battalion consolidated, then drove off a German counter-attack at 17.30, capturing 180 prisoners and five machine guns in the process.

On 23 August, reinforced by two companies of 1st DCLI, the battalion launched an attack at 11.00 behind a creeping barrage to capture the railway line.

[22][11][56][57][58] The weakened battalion was withdrawn into reserve while the rest of 95th Brigade attacked on 30 August (the Battle of the Scarpe) and then took over holding part of the front line.

The BEF's Third Army stormed across the Canal du Nord on 27 September, and next morning 5th Division launched a follow-up attack.

It ran into considerable opposition and 12th Gloucesters found both its flanks were open; 1st DCLI came up on the left later, but the right remained exposed and isolated German machine gun posts had to be dealt with using rifle grenades.

12th (Service) Battalion, Gloucestershire Regiment, (Bristol's Own) commenced disbandment on 19 October 1918 while the Battle of the Selle was raging.

[69][70] Between 21 November 1915 and 26 March 1916, all ranks of the battalion wore a horizontal strip of ribbon, purple-over-yellow-over-purple, on the back beneath the collar.

[71] The division did not wear unit identification patches, but used markings painted on the steel helmet: during 1918, 12th Glosters wore a black circle.