Comprising mainly infantry battalions from Yorkshire and Lancashire, the division was sent to Egypt in December 1915 before moving to France in March 1916 and spent the remainder of the First World War in action on the Western Front.

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 Army, and on 11 August the newly-appointed Secretary of State for War, Field Marshal 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.

[6][7] On 29 November 1915 the division received warning orders to join the British Expeditionary Force in France, and advance parties set out for the embarkation ports of Folkestone and Southampton.

It also provided working parties to assist the 252nd Tunnelling Company, Royal Engineers, digging the Hawthorn Ridge mine that was to be exploded to launch the forthcoming Battle of the Somme.

[6][10] The 92nd Brigade held the front line trenches during the British bombardment in the days leading up to the battle, suffering significant casualties from the German counter-bombardment.

The night before the battle, working parties from the 92nd Brigade were out in No man's land cutting lanes through the British barbed wire for the assaulting troops to pass through.

[11][12][13][14][15] On 2 July the shattered division was pulled out of the line and sent north to a quiet sector for rest and refit, though there was the usual trickle of casualties associated with trench holding and raiding.

[16] The Somme Offensive was still going on at the end of October when the 31st Division returned to the sector for the Battle of the Ancre, which was to be the last big operation of the year.

Zero hour was 05.30 on 13 November, and fog, light rain and a smokescreen reduced visibility to a few yards, so that the leading battalions initially had little difficulty, but the 3rd Division on their right made no progress.

The British creeping barrage started at 03.45 and the 92nd and 93rd Brigades set off, in the dark and mist, into severe machine gun fire from Oppy Wood.

[23][24] The 31st Division was not committed to the Third Ypres Offensive, which culminated in the dreadful Battle of Passchendaele, possibly because it was not considered to have recovered from its ordeal on the Somme a year before.

[25] By the beginning of 1918 the BEF was suffering a severe manpower crisis: brigades were reorganised on a three-battalion basis in February, with the surplus men being drafted to bring other units up to strength.

There was fighting in the village streets, but the next day the combined fire of 92nd Brigade and part of 42nd (East Lancashire) Division stopped the German advance.

[35][36][37][38] Individual units continued to make small advances through aggressive patrolling and seizing strongpoints (so-called 'peaceful penetration') until the Allies began a coordinated offensive in August.

The general retirement of the Germans along the whole line then allowed the division to push on through Ploegsteert Wood and advance up to the River Lys on 3 October.

[44][45][46] The division was back in the line from 28 October, with the 92nd Brigade in the lead continuing to advance slowly against machine gun and shell fire, from rearguards who 'did not appear disposed to give ground'.

[6][47][48] The 31st Division returned to the line on the night of 6/7 November, crossing the Scheldt and sending forward the 11th East Yorks as part of a pursuit force including a field artillery battery and companies from the divisional machine gun battalion, the Motor Machine Gun Corps and XIX Corps cyclists.

When the Armistice with Germany came into force on 11 November, the 11th East Lancs were leading the division, and scouts reported that there were no enemy in front.

[6][49][50][51] The division began to pull back on 13 November, and by the end of the month was established in camps south of St-Omer and engaged in road repair.

On 29 January the two East Yorks Battalions were sent by rail to Calais to deal with possible riots by men working in the Ordnance depot.