It became the engineer component of the 42nd (East Lancashire) Division of the Territorial Force, seeing service in Egypt, at Gallipoli and (together with a duplicate unit) on the Western Front during the First World War.

Nos 1 and 2 Sections of 1/1st Fd Co and signal detachments were engaged in the fighting at Tussum on 3–4 February 1915, the Sappers holding the west bank of the canal and suffering their first casualties.

The sappers were issued with camel transport and moved up to the railhead at Pelusium, then 1/1st and 1/3rd Fd Cos accompanied two brigades of 42nd (EL) Division in the pursuit to Katia Oasis after the Battle of Romani (3–5 August).

On 6 September 125th Bde made an attack on the strongpoints of Iberian, Borry and Beck House farms, for which the RE prepared dumps of wiring material to consolidate the captures.

[53][54] After the victory of the Battle of Amiens on 8 July – the start of the Allied Hundred Days Offensive – the Germans in front of 42nd (EL) Division began to withdraw.

In two continuous days of fighting (the Battle of the Canal du Nord, 27–28 September) the East Lancashires leap-frogged through five successive objectives, with the sappers clearing the Hindenburg Line dugouts of booby-traps.

Then on 19 October, the night before the attack, they built four more footbridges and two Pontoon bridges under machine gun fire and gas shelling, but only suffered six casualties.

The Signal Company struggled with over 50 per cent casualties from the Spanish flu outbreak and from combat (at one point No 3 Section were fighting as infantry alongside 126th Bde).

[20][21][62][63][64] After the Armistice the divisional engineers still had a heavy commitment to bridge repair and constructing winter accommodation for the division in the Charleroi area until February 1919, but thereafter demobilisation began in earnest.

On 20 March the division sidestepped to the Hohenzollern Redoubt sector, where it carried out two trench raids in which RE parties accompanied the infantry to blow in enemy dugouts.

At the end of June the division moved to the Flanders coast where it joined Fourth Army preparing to advance in support of the expected breakthrough at Ypres.

The infantry had a bad time in their first major battle at Poelcappelle on 9 October, but the RE were mostly engaged in roadmaking and making timber platforms to stop heavy artillery sinking into the mud.

The divisional RE and the newly joined pioneer battalion, 1/5th Bn Border Regiment, were put to work on new defences to meet the expected German Spring Offensive.

The line was turned elsewhere, and for the next few days of retreat the sappers took part in a series of stands while destroying camps and dumps before they fell into enemy hands.

The divisional RE, which still had half its manpower, was split up: 430th Fd Co remained with the division while the other two became GHQ troops, directing Chinese and Portuguese labour battalions in constructing new defence lines through the summer months.

[68][69][79] 66th Division was reformed on 18 September 1918, mainly with non-Lancashire units including the South African Brigade, and the divisional RE marched to rejoin it near Arras.

[68][69][82][83] The division returned to the front and on 9 November part of it joined 'Bethell's Force' under the divisional commander, Maj-Gen Hugh Bethell, to continue the pursuit.

[89][91][92][93] After assembling in Lancashire, 73rd Division moved in early January 1917 to join Southern Army (Home Forces), stationed in Essex and Hertfordshire.

[100][103][104][105][106][107][108][109] 202 (East Lancs) Fd Co continued to serve with 52nd (Lowland) Divisional RE for the rest of the war, including a brief expedition to France as part of the 'Second BEF' after Dunkirk, and then in the Campaign in North West Europe in 1944–45.

[103][105] When the German offensive in the west opened on 10 May, the BEF advanced into Belgium in accordance with 'Plan D', with 42nd (EL) Division moving up to the Escaut, where it was in reserve, the RE preparing bridges for demolition.

One of its crews became the first sappers to enter Germany, though their vehicle was trapped in a cutting, lost its bridge, and remained on the German side of the frontier all night under fire.

The third troop distinguished itself by pushing an 80 feet (24 m) Bailey bridge some 4.5 miles (7.2 km) on icy roads using a skid of their own devising to cross a crater north of Geilenkirchen.

Captain Herbert Baynton-Jones of 222 Sqn was awarded an MC for dismounting to take control of an RE mineclearing detachment and then leading his troop of AVREs to attack a village with their petards.

Led by Staff Sgt Sweeney of RHQ 42nd Assault Rgt the dozer crews had to deal with snipers and enemy infantry and machine gun posts before they could reach the intended exit point.

42nd Assault Rgt operated its ferries until the afternoon of 26 March when a Bailey bridge was completed, during which period it carried 311 tanks and self-propelled guns and a few wheeled vehicles.

The RE units with IX Corps built approach roads for the attack on Kairouan to cut off the Axis retreat during the Battle of Wadi Akarit.

For the corps' next advance 558 Fd Co was among the sappers tasked with preparing 20 miles (32 km) of hill tracks in No man's land for an armoured thrust; to achieve surprise most of this work was completed at the last moment.

On IX Corps' front it was initially successful, but then efforts to find a way through for the armour added another 100 miles (160 km) of sand tracks to the road maintenance commitment.

[162] The Supplementary Reserve company attached to 42nd Divisional Engineers, 104 (East Lancs) Army Troops Co, also went to France in 1940 working on the BEF's Lines of Communications.

[174] A memorial plaque with the 41 names of the 42nd (EL) Signal Company who died on service during the First World War was unveiled at the Brooks Bar drill hall on 21 October 1934.