In all 26 allied divisions served in the salient from 1915-18 including two French and all four Canadian units. The longest serving was the territorial 46th (North Midland) Division with 13 months in the line. Every corner of the British Isles and almost every dominion of Empire provided troops for what became the apotheosis of trench warfare.

In 1939 war returned once again to the Salient as the Hulluch  tunnels dug by the British in 1916 were occupied by sappers of a new British Expeditionary Force (BEF), re-engineering them for use as a headquarters for Lt General Sir Alan Brooke’s II Corps. But in May 1940 the Germans began their invasion of France and Belgium, the BEF moved forward to engage them and the Hulluch tunnels were once again abandoned.

Seventy five years later they would be opened up once more - by members of the Durand Group.

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Towards the end of 1917 Australian tunnellers further strengthened the defensive positions in the Loos Salient, installing anti-infiltration measures in the tunnels and anti-tank obstacles on the surface to thwart an expected German offensive in the spring of the following year. ‘Operation Valkyrie’, as it was known in 1918, never materialised, although British forces to the north and south of it bore the brunt of the German onslaught as it passed them by.

87 kilometres of fighting and communication tunnels,  at multiple levels.


But by mid May the Germans had begun to run out of steam, both psychologically and logistically. By September they were in general retreat and on 19th October 1918, just four years on from its occupation, the Loos Salient, including Lens and La Bassée was finally liberated. Every aspect of it had been totally destroyed and it would be almost a decade before the communities would begin to experience some semblance of normality.

Loos, Fosse 15 and its Crassier (IWM Q43113) Film: Mining Activity on the British Front Chlorine Gas Cylinders Canadians resting near Hill 70, Aug 1917 Ruins of Fosse No.5, Loos-en-Gohelle

The Loos Salient 1915-2018

"..the Black Country of France, scattered with mining villages in which every house was a machine-gun fort, with slag heaps and pit-heads which were formidable redoubts, with trenches and barbed wire and brick-stacks, and quarries, organized for defence in siege-warfare, cavalry might as well have ridden through hell with hope of "exploiting" success.."

War Correspondent Phillip Gibbs

In October 1914 the advancing German 6th Army overran Lens together with its neighbouring towns and villages. XIV Armee Korps soon established a strong front line to the west of Loos-en-Gohelle, from Grenay northwards to the La Bassée canal at Cuinchy. In early 1915, immediately in front of Loos-en-Gohelle, they constructed a second ‘Village’ line, flanked by two formidable machine-gun redoubts - Fort Glatz and Stützpunkt 69, comprising deep dugouts and trenches protected by thick barbed wire entanglements. Further back still another defensive line was under construction, with yet more fortified redoubts, running parallel with the route national from Lens, through Hulluch, to La Bassée.

“The Battle of Loos” grew out of a much grander French Army offensive in the Artois and Champagne, conceived by Marshal Joseph Joffre, head of the French army, to expel the enemy from her soil and take pressure off the crumbling Russian armies in the east.

           On a 20 mile front between Arras and the La Bassée Canal, the Artois part of the offensive would involve General D'Urbal's French Tenth Army, together with General Sir Douglas Haig's British First Army. Both would be augmented by subsidiary attacks on other fronts to prevent enemy reserves moving in support of the main assault.

The British were to capture ground inclusive from the La Bassée Canal, south to Hill 70, overlooking Lens, then head for the Haute Deule canal, at which point their cavalry could be moved up. After capturing the Douai Plain the French cavalry would press on towards Valenciennes within striking distance of the Belgian frontier.

“The Battle of Loos”, together with “Actions at the Hohenzollern Redoubt”, was fought between 25th September and 15th October 1915. 163 British infantry battalions were involved on a front stretching from Grenay, north to Givenchy: 117 English, 38 Scottish, 7 Welsh, 2 Irish.

The result: 48,367 British casualties - 46% killed or missing - with a disproportionate number of officers amongst them, including three major generals. 22 Victoria Crosses were awarded during the battle, including three at subsidiary locations further north.

From 30th September - 31th December two French Divisions -17th & 18th - held the line at Loos, in support of the British, fending off a number of fierce German counter-attacks.

47th (2nd London) Division attacking at Loos

The battle was also notable for the first British use of poison gas in the assault - over 5500 cylinders containing 150 tons of chlorine. It also heralded the first significant use of Kitchener’s New Armies - 9th and 15th (Scottish), 21st (Northern) and 12th and 24th (Eastern) divisions; and a number of technical and tactical innovations including indirect machine gun fire and Chinese attacks. Significant for one other reason: it resulted in the eventual sacking of the BEF Commander in Chief, Field Marshal Sir John French and the promotion of his immediate subordinate - General Sir Douglas Haig.

Neither did the Battle of Loos achieve its secondary objectives: to encircle Lens from both flanks, re-establish a war of movement and in the process take re-possession of several of the important mining assets in the region including Lens. What it did do was to establish a vulnerable salient into which the Germans could direct all their artillery resources with impunity for the next three years, reducing many of the local communities to rubble and destroying what remaining mining infrastructure still existed.

From a strategic point of view the Loos Salient then became somewhat of a backwater - both sides gradually and reluctantly accepting that the war would probably not be won or lost there. It therefore became an ideal nursery for reintroducing those medieval tactics that characterised so many earlier conflicts in history - the art of siege warfare - and it did so for three years from the end of 1915 until the armistice in 1918. As the lines stabilised specialised tunnelling companies were deployed and mining sectors were established, from south to north in the Salient - Double Crassier, Copse, Hill 70, Chalk Pit, Hulluch/St Elie, Hairpin, Hohenzollern, Cuinchy as far north as Givenchy and the La Bassée canal. Here men lived, moved and fought each incessantly for almost three years burrowing in a myriad of dugouts, subways and tunnels - a troglodyte world so extensive that some of the underground installations could be seen as communities in their own right. From 1915 -1916 over 300 mines were fired between Grenay and Givenchy in an eleven month period.

By mid 1917 the mining war in this sector had subsided. But the German Pioneers continued to deploy their highly effective minenwerfers -(trench mortars) - to harry the British, causing worrying casualties and constant damage to the trenches. In response the British tunnellers, later augmented by 3rd Australian Tunnelling Company, began an ambitious underground communication scheme. Within six months dozens of infantry tunnels - subways - were constructed within the Salient to protect the troops. Most extensive was the Hulluch system of tunnels, containing all manner of command and control facilities:

"To the north of Lens near Hulluch, where I went through the workings with Sanderson, the whole defence of the front appears to be underground. The infantry garrison lives underground, trench mortars and their crews are underground. The machine guns are underground and for a mile behind the front line the communication trenches are underground. The light railway delivers stores to the gun emplacements by an even lighter railway - underground!"

Charles Bean, Australian Official Historian of the Great War

In August 1917, in an attempt to draw German reserves away from the Ypres Offensive to the north or at least hold existing units within the Loos Salient, the Canadian Corps, supported by British divisions, was tasked with capturing Hill 70 and the suburbs of Lens. The assault met with only partial success although it did gain more ground and put increased pressure on Lens itself. Five Canadian and two British VCs were awarded in the fierce fighting.

But the capitulation of Russia in the autumn had profound consequences in that it released hundreds of thousands of German and Austro-Hungarian troops from the eastern front for service in the west. Here the German High Command needed a decisive victory, before the Americans could arrive in strength and whilst France was still recovering from her mutinous episode.

Plan of Hythe Subway near Hill 70 (3rd Australian Tunnelling Company) 1918