During World War I it raised four battalions, which carried out garrison duty in Malta and Egypt, served at Gallipoli and against the Senussi, and saw a great deal of action on the Western Front, notably in the Attack on the Gommecourt Salient in 1916, at Bullecourt in 1917 and at Oppy Wood and Chipilly Ridge in 1918.

Four officers and a small number of NCOs and men ruled medically unfit for overseas service were left at Hoxton to begin recruiting a reserve battalion.

[35] After this, the reinforcement problems meant that the Indian Corps was not used offensively for the rest of the year, and 1/4th Londons spent the summer of 1915 taking turns in holding sections of trench in the La Bassée Road area and providing working parties while suffering a trickle of casualties.

It was the same story when the division made a second attempt on 18 September: this time the battalion came under heavy German fire, lost a good many men, and had to shelter in muddy shell-craters until the attack was called off.

The remaining attackers lay out in No man's land, no further than 50 yards from their starting position, trying to get round the gun pits, until darkness began to fall and German counter-attacks developed.

[70][71] In March 1917 the 56th Division was preparing to attack as part of the forthcoming Battle of Arras when patrols discovered that the Germans in front had disappeared – the beginning of their retreat to the Hindenburg Line.

The battalion was in support for the attack, B Company advancing to 'mop up' behind the Rangers and 1/13th Londons (Kensingtons)), the remainder moving forward in the afternoon to fill a gap in the line and then consolidate.

At a late stage 1/4th Londons were attached to the weak 53rd Bde for this operation, but the CO, Lt-Col H. Campbell, was wounded on the way to meet the brigadier, and his second-in-command had less than 24 hours to reconnoitre and prepare the attack, in muddy terrain, with the start line changed at the last moment.

The battalion left its mud holes and followed the barrage at 05.45 on 16 August, but 7th Bn Bedfordshire Regiment was unable to take a concrete pillbox, which caused many casualties to the 1/4th Londons, who were brought to a standstill and could do no more than form a defensive flank along the edge of Glencorse Wood.

The 1/4th Bn prepared a defensive flank facing south in case the line was turned, but no attack developed until 03.00 on 28 March (Operation Mars) when the battalion's outposts in Oppy Wood came under heavy bombardment.

The other two companies in the support trench (the Marquis line) then held the attackers while the defensive flank (Ouse Alley) was manned by details from Advanced Battalion HQ, and artillery fire was brought down on the captured outposts.

[87][88][89] Relieved and moving to a rest area, the 1/4th Bn was lucky to receive two drafts of fully trained reinforcements totalling 420 men, but they came from all over the UK, diluting the Cockney nature of the battalion.

The battalion resumed the advance at 16.30, attacking in widely extended formation and suffering few casualties, capturing machine guns and patrolling 500 yards beyond the Germans' Boyelles Reserve trenches.

[23][27][105][106][107] While on Malta the 2/4th Bn was stationed at St George's Barracks and continued training, being issued with Long Lee–Enfield rifles and carrying out a musketry course under sergeant-instructors from the Royal Marine Light Infantry.

The battalions handed in their Long Lee–Enfields and drew modern Short Magazine Lee-Engfields in their place.On 17 April the brigade left 53rd (Welsh) Division and embarked on HMT Transylvania for Marseilles.

[2][12][129] At the time of the renumbering, the 58th Division was carrying out coast defence duties in East Anglia, but on 10 July 1916 it concentrated at Sutton Veny for final training on Salisbury Plain.

Leake of C Company was recommended for a VC and was awarded an immediate DSO for single-handedly ejecting a German machine gun team attempting to take up a position to enfilade his men.

2/4th Londons were detailed to leap-frog through and take 173rd Bde's second objective, but the exhausted men, with hardly a rifle able to fire because of the mud, only took one post, at Tracas Farm before being pushed back to their start line.

Most of C Company at the Triangle locality, supported by a single 18-pounder field gun, were eventually captured, but by midnight the rest of the battalion had withdrawn in good order across the Crozat Canal.

[144][145][146] The mixed force under 173rd Bde held out on the fourth day of the battle until the afternoon, when they made a planned withdrawal, and by 16.30 had retired across the Oise to join the rest of 58th Division.

An 18-pounder gun was manhandled to Lt-Col Dann's Bn HQ, where it drove back the remaining German tanks, A counter-attack the following day regained Villers-Bretonneux and most of the lost ground.

A dawn attack on 25 August found the German positions empty, and 2/4th Londons was sent forward with a Troop of the Northumberland Hussars and sections of the Royal Field Artillery and Machine Gun Corps as an advanced guard to re-establish contact with the enemy.

In these unusual conditions of open warfare, the battalion marched in column up a road until the cavalry contacted the enemy at Billon Wood, when the companies deployed and attacked.

The battalion followed the creeping barrage, overcame some resistance at the edge of the village, and was on its final objective by 10.45 – an advance of 3000 yards representing the most successful action fought by the 2/4th Bn.

Despite the successes of the Hundred Days campaign, the BEF's manpower crisis was now severe, and on 12 September 1918 the remnant of the 2/4th Bn was absorbed by the 2/2nd Londons, which fought on with 58th Division until the Armistice in November 1918.

[221][223] By early 1943 it had become a mobile unit once more as part of the field force under WO control with the following composition:[224] The regiment was assigned to Second Army for the Allied invasion of Normandy (Operation Overlord).

There was little activity by the Luftwaffe, but on 17 December it carried out strikes all along the Allied front, with Focke-Wulf Fw 190s and Messerschmitt Bf 109s attacking the Waal bridges and artillery positions at low level.

On 1 January 1945, the Luftwaffe launched Operation Bodenplatte: daylight attacks by single-engined fighters against Allied airfields and lines of communication in support of the Ardennes offensive.

King's colours were presented to the war-formed TF battalions in 1921: that of the 2/4th is laid up in the Officers' Mess at the Army Reserve Centre, Balham High Road, while that of the 3/4th is in the Fusiliers Museum at the Tower of London.

[249] The 4th London Regiment was awarded the following Battle honours:[10][12] South Africa, 1900 Neuve Chapelle, Ypres, 1915, '17, St Julien, Aubers, Festubert, 1915, Somme, 1916, '18, Albert, 1916, '18, Guillemont, Ginchy, Flers-Courcelette, Morval, Le Transloy, Arras, 1917, '18, Scarpe, 1917, '18, Bullecourt, Langemarck, 1917, Menin Road, Polygon Wood, Passchendaele, Cambrai, 1917, '18, St Quentin, Villers Bretonneux, Amiens, Bapaume, 1918, Hindenburg Line, Canal du Nord, Valenciennes, Sambre, France and Flanders 1915–18, Gallipoli 1915–16, Egypt, 1916.