Working feverishly while under attack from shells, machine guns and mines, civil engineers played a key role in the Allied victory on the Western Front, whose 80th anniversary is commemorated next week.
Boring tunnels from which to mount mine attacks and constructing river crossings for advancing infantry in the face of an enemy barrage were among the main tasks faced by engineers at the battle front in northern France.
Responsible for offensive and defensive tasks, and maintenance of communication lines, the Royal Engineers totalled just over 6,500 men at the start of the war. ICE members helped to make up the early shortfall of officers but by November 1918 RE ranks had swelled to nearly 350,000.
Engineer in chief to the British Army in France, Major General Moore- Heath, summed up the revolution in war engineering in 1919: 'The vast organisation of engineers needed was not anticipated. Our pre-war military advisers had little conception of the scale on which modern engineering methods would be applied in a great European war,' he wrote in ICE's Proceedings in 1919.
By the end of 1914 both sides on the Western Front had settled down to slow moving trench warfare. For the next three years the tunnelling operations of the REs were a key element in the drive to break the stalemate.
Tunnelling underneath the front line and across no man's land to blow up the enemy's trenches was often an underground game of cat and mouse between the RE and their German counterparts. As they tunnelled towards each other, the winner was the first to detect the presence of the other.
'To make certain of destroying the enemy, listeners at the face of the mine had to judge the distance of the enemy's approach, and go on listening until the enemy is judged to be within 10 feet of their own gallery. It was often a race as to which side would get their charge in first and it was not always we who won,' wrote Moore-Heath.
Allied tunnelling in France - which in 1916 resulted in 867 offensive mine explosions to Germany's 802 - peaked with the blowing up of the heavily fortified Messines Ridge near Ypres on 7 June 1917. In his book The Sapper VCs, Gerald Napier quotes an eyewitness as saying: 'It seemed as if the Messines ridge got up and shook itself. All along its flank belched rows of mushroom shaped masses of debris flung into the air.'
In history's biggest offensive mining operation, 19 mines comprising a million pounds of explosives were laid over two years in an intricate network of tunnels. The eventual explosion devastated enemy lines and the ridge was captured.
Bridge building was the other operation which thrust civil engineers into the front line. The Royal Engineers established a bridging school in 1916 which developed wooden trestle bridges and pontoons. Some bridges had to be strong enough to carry the 16 ton, six inch guns and 30 ton tanks used in the final phase of the war, and between August and November 1918, 326 steel joist bridges were constructed for bridging canal locks.
During the rapid Allied advance from August to November 1918, retreating German forces blew up all bridges in their wake, making speedy temporary bridge construction vital to the continued advance. In one case, when materials ran out, a lance corporal and three sappers ignored machine- gun fire to dash into the water and hold up planks while infantry ran over them.
The Allied crossing of the Sambre-Oise canal was the final act of the war in November 1918. A vital blow was struck by the breaking of the canal defence line in northern France because it gave access to German supply lines. During the foggy dawn on 4 November, the REs began working from rafts improvised from petrol tins to build foot bridges for the troops across the 70ft wide canal. By the end of the day two pontoon and trestle bridges were taking traffic.
Infantry arriving at the front soon became aware of RE support activity behind the Allied lines. Approaching the muddied 16km network of trenches behind the Western Front, soldiers would have seen the rail tracks along which pack animals drew the trucks carrying guns and ammunition. Initially the tracks were made of timber, but this was gradually replaced by steel so that by spring 1917, the REs had built 3,200km of normal gauge railways.
Arriving soldiers would also have seen the shell holes that devastated the French road network. By the battle of the Somme in 1916, the engineers improvised new roads by laying down 10ft hardwood planks over the mud: nearly 6M of these were used for road making.
The building of roads and track serving the front accelerated after the huge British led offensive at the Somme in 1916.
'It took the battle of the Somme in 1916 and all its lessons to drive home the obvious fact that large numbers of men and guns, in the dense concentrations required by modern war, are useless without a highly organised system of transportation to supply their needs,' wrote Moore-Heath.
Engineers also helped to improve the soldier's lot. Cases of trench foot in the waterlogged conditions were reduced after an ICE commission recommended the construction of large pumping stations and graded drains.
The shortage of water for men and horses was quickly allayed by a network of pipelines close to the front. For the battle of the Somme, 200km of four inch pipe was laid in preparation. A purification plant built in Belgium enabled the Allies to take 275,000 litres a day of impure water from the River Yser and pump it to the troops.
Armed with the 'very stubborn sort of courage necessary for carrying out engineer duties', engineers were also praised as excellent fighting men when called upon. Many of the 957 officers and 16,250 other ranks of Royal Engineers who died were killed as auxiliary infantrymen when caught in desperate rearguard actions.
Moore-Heath wrote: 'Under great pressure, engineers often had to serve as infantry in defence of villages, in rearguard actions, and in counter attack, having more than once saved the situation by their individual skill and courage. Individuality is induced by an engineer education.'
An exhibition of photographs and documents from the First World War is displayed in glass cases opposite the ICE's war memorial at Great George Street.