The Actions of the Hohenzollern Redoubt took place on the Western Front in World War I from 13 to 19 October 1915, at the Hohenzollern Redoubt (Hohenzollernwerk) near Auchy-les-Mines in France. In the aftermath of the Battle of Loos (25 September – 8 October 1915), the 9th (Scottish) Division captured the strongpoint and then lost it to a German counter-attack. The British attack on 13 October failed and resulted in 3,643 casualties, mostly in the first few minutes. In the History of the Great War, James Edmonds wrote that "The fighting [from 13 to 14 October] had not improved the general situation in any way and had brought nothing but useless slaughter of infantry".
In the summer of 1915 the German armies continued the strengthening of front trenches, communication trenches and strong-points ordered by Chief of the General Staff General Erich von Falkenhayn, who on 25 January had also ordered the building of more defensive lines behind the front trench. Crown Prince Rupprecht the Sixth Army commander and some Western Front generals had objected to this policy, as an invitation to German troops to retreat rather than fight. After the experience of the Battle of Festubert, where Allied artillery had proved capable of destroying a great width of front trench, opposition had been abandoned and the work carried on as quickly as possible. In early May Falkenhayn had also ordered that a second defensive position be built 2,000–3,000 yd (1.1–1.7 mi; 1.8–2.7 km) behind the whole of the Western Front, to force an attacker to pause to move artillery forward into range.
Plans to exploit the Franco-British superiority in numbers on the Western Front, while one third of the German army was on the Russian Front were agreed at a Conference by Joffre and French at Chantilly on 14 September. The British New Armies had begun to arrive, the number of heavy guns had increased since the offensives of May and June and by concentrating resources at the points of attack an even greater numerical superiority could be obtained over the Germans. An unprecedented preliminary bombardment of the German defences would be possible and make attacks by the greater number of Allied infantry decisive. Simultaneous offensives would be mounted from Champagne and Artois towards Namur, the principal attack being made in Champagne.
The attack by the French Tenth Army on Vimy Ridge in May and June had failed, which left the German Sixth Army in control of the high ground below which the French were to have assembled a mass of artillery and infantry. It was agreed that in Artois a Franco-British offensive would be mounted towards Douai, by the French Tenth and the British First armies, co-ordinated by General Foch on a front of 20 miles (32 km) between Arras and La Bassée canal. The British First Army was to attack between Grenay and La Bassée canal on a 6-mile (9.7 km) front, with six divisions and three in reserve. The Cavalry Corps and Indian Cavalry Corps were to be held ready to exploit a German collapse. The Franco-British armies were to attack towards Tournai, Valenciennes and Le Quesnoy and subsidiary attacks were to be made by the rest of the Franco-British armies to pin down German reserves.
Field artillery available to the British divisions covered a 1-mile (1.6 km) front, with 19 heavy guns in support, while the Tenth Army divisional frontages were .75-mile (1.21 km) wide with 35 heavy guns. The smaller number of British guns was matched by a lack of ammunition. The offensives were to begin with a continuous and methodical bombardment for 96 hours, in which counter-battery fire was as important as trench destruction. A four-hour intense bombardment was to be fired, before the infantry attacks in Artois and Champagne began simultaneously on 25 September. The infantry were to advance as an "irresistible mass", with reserves arranged in depth to move forward at the same time as the leading troops, ready to take over and maintain the momentum of the assault. Previous attacks in Artois had been obstructed by the many villages and industrial premises in the region, which were easy for the Germans to fortify and use to delay attacks. The Franco-British heavy artillery was to be used to destroy German fortified houses and villages, which were proof against field artillery. Such tactics were expected to break through both German defensive positions and enable the cavalry to rush forward and widen the breakthroughs, before advancing on distant objectives in Belgium. If the attacks succeeded the rest of the Franco-British-Belgian armies would join in a general offensive and force the German armies into open warfare, in which Allied numerical superiority would be overwhelming.
British offensive preparations
The artillery of the 9th (Scottish) Division was arranged in two mobile groups and a reserve. One field artillery brigade supported each of the two attacking infantry brigades and two howitzer brigades with a mountain battery, were held back for counter-battery fire and targets of opportunity on the divisional front. The three brigade field companies of the Royal Engineers and the pioneer battalion were placed in reserve. Two 9.2-inch howitzers were dug in near a wood at Beuvry with arrangements made for ground and air observation of their fire and Russian saps were dug towards the redoubt. On the night before the attack the saps were opened and the ends joined, to make a jumping-off trench 150 yards (140 m) away from the face of the redoubt.
The 9th Division commanded by Major-General George Thesiger was to attack with 26th Brigade and 28th Brigade on a front of 1,500 yards (1,400 m) between the left flank of the 7th Division and the Vermelles–La Bassée railway to capture the German front and support trenches. The divisional objectives were the buildings and dump of Fosse 8 and the Hohenzollern Redoubt. The Dump was a flat-topped spoil-heap 20 feet (6.1 m) high with a commanding view and had been made the principal German observation post in the area. When captured The Dump would give the British observation over Haisnes and St. Elie. On the right the 26th Brigade with two battalions, was to overrun the Hohenzollern Redoubt and Fosse 8 in the first rush. The two supporting battalions would then attack south of the fosse and advance on Haisnes, while the leading battalions reorganised to follow on in support, as the fosse was consolidated by the 28th Brigade. The division was then to capture the redoubt, The Dump and Fosse 8 before advancing to the Lens–La Bassée road; after reaching the road the division was to press on to the German second position between Cité St. Elie and Haisnes. The 27th Brigade in reserve, was then to advance through Douvrin to the Haute Deûle Canal (Canal de la Deûle), with the 7th Division on the right flank; XI Corps would then pass through to continue the advance.
A number of pit-heads known as Fosses and auxiliary shafts called Puits had been built around Loos, when the area was developed by the mining industry; Fosse 8 de Béthune was close to the north end of a spoil-heap (Crassier) known as "The Dump". The Crassiers had been tunnelled or hollowed out by both sides, to provide observation-posts and machine-gun nests. The Dump was 20-foot (6.1 m) high, with an excellent view in all directions. New fortifications were built as quickly as possible, after the Franco-British offensives in May and June 1915. At Dump and Fosse trenches, on a slight rise 400 yards (370 m) in front of the original front line, a new defensive work wired for all-round defence was built and named the Hohenzollernwerk. The face of the redoubt was 300 yards (270 m) long and curved, with extensions to join with "Big Willie" Trench to the south and "Little Willie" Trench to the north. British planners judged the Hohenzollern Redoubt to be the strongest defensive-work on the whole of the front. In the area of Fosse 8, more fortifications were built in July by the German 117th Division, after it had fought at Vimy Ridge in May and June; once a period of reorganisation at Roubaix was over, the division returned to the line on 9 July.