Operations on the Ancre took place from 11 January to 13 March 1917, between the British Fifth Army and the German 1st Army, on the Somme front during the First World War. After the Battle of the Ancre (13–18 November 1916), British attacks on the Somme front stopped for the winter. Until early January 1917, both sides were reduced to surviving the rain, snow, fog, mud fields, waterlogged trenches and shell-holes. British preparations for the Battle of Arras, due in the spring of 1917, continued.
The Fifth Army was instructed by the commander in chief of the British Expeditionary Force (BEF), Field Marshal Sir Douglas Haig, to make systematic attacks to capture portions of the German defences, to pin down German troops. Short advances could progressively uncover the remaining German positions in the Ancre valley to ground observation, threaten the German hold on the village of Serre to the north and bring German positions beyond into view. Artillery-fire could be directed with greater accuracy by ground observers and make German defences untenable.
A more ambitious plan for the spring was an attack into the salient that had formed north of Bapaume, during the Battle of the Somme in 1916. As soon as the ground dried, the attack was to be made northwards from the Ancre valley and southwards from the original front line near Arras to the north, to meet at St Léger and combine with the offensive due at Arras. British operations on the Ancre from 11 January to 22 February 1917 forced the Germans back 5 mi (8.0 km) on a 4 mi (6.4 km) front, ahead of the scheduled German retirements of the Alberich Bewegung (Operation Alberich) and eventually took 5,284 prisoners.
On 22/23 February 1917, the Germans withdrew another 3 mi (4.8 km) on a 15 mi (24 km) front. The Germans then withdrew from much of Riegel I Stellung (Reserve Position I) to Riegel II Stellung (Reserve Position II) on 11 March, which went unnoticed by the British until dusk on 12 March, forestalling a British attack. Unternehmen Alberich, the main German withdrawal from the Noyon salient south of the Somme, towards the Hindenburg Line, commenced on schedule on 16 March.
Background
German defences
By the end of 1916, the German defences on the south bank of the Ancre valley had been pushed back from the original front line of 1 July 1916 and were based on the sites of fortified villages connected by networks of trenches, most on reverse slopes sheltered from observation from the south and obscured from the north by convex slopes. On the north bank, the Germans still held most of the Beaumont-Hamel spur, beyond which to the north were the original front line defences, running west of Serre and then northwards to Gommecourt and Monchy-au-Bois. The Germans had built Riegel I Stellung (Reserve Position I), a double line of trenches and barbed-wire several miles further back from Essarts to Bucquoy, west of Achiet-le-Petit, Loupart Wood, south of Grévillers, west of Bapaume, Le Transloy to Sailly-Saillisel as a new second line of defence along the ridge north of the Ancre valley.
On the reverse slope of the ridge, Riegel II Stellung (Reserve Position II) ran from Ablainzevelle to west of Logeast Wood, west of Achiet-le-Grand, western outskirts of Bapaume, Rocquigny, Le Mesnil en Arrousaise to Vaux Wood. Riegel III Stellung (Reserve Position III) branched from Riegel II at Achiet-le-Grand clockwise around Bapaume, then south to Beugny, Ytres, Nurlu and Templeux-la-Fosse. The first two lines were also known as the Allainesstellung and Arminstellung by the Germans and had various British titles (Loupart Line, Bapaume Line, Transloy Line and Bihucourt Line, the third line was known as the Beugny–Ytres Switch). The 1st Army held the Somme front from the River Somme north to Gommecourt and had a similar number of troops to the British opposite, with ten divisions in reserve. On the night of 1/2 January, a German attack captured Hope Post near the Beaumont Hamel–Serre road, before being lost along with another post on the night of 5/6 January.
British positions
The Fifth Army held about 10 mi (16 km) of the Somme front in January 1917, from Le Sars westwards to the Grandcourt–Thiepval road, across the Ancre east of Beaucourt, along the lower slopes of the Beaumont-Hamel spur, to the original front line south of the Serre road, north to Gommecourt Park. The right flank was held by IV Corps up to the north side of the Ancre river, with the XIII Corps on the north bank up to the boundary with the Third Army. II Corps and V Corps were in reserve resting, training and preparing to relieve the corps in line around 7–21 February, except for the divisional artilleries, which were to be joined by those of the relieving divisions.
An advance to close up to the Le Transloy–Loupart line (Riegel I Stellung), which ran from Essarts to Bucquoy, west of Achiet le Petit, Loupart Wood, south of Grévillers, west of Bapaume, Le Transloy to Sailly Saillisel, had been the first objective of British operations in the Ancre valley after the capture of Beaumont Hamel in late 1916. Operations began with an attack on 18 November, before the deterioration of the ground made operations impossible. Ground had been gained on a 5,000 yd (2.8 mi; 4.6 km) front south of the Ancre and positions improved on Redan Ridge on the north bank. Over the winter, the Fifth Army submitted plans to General Headquarters (GHQ), which were settled in mid-February, after Joffre was replaced by General Robert Nivelle and the changes of strategy caused by the French decision to fight a decisive battle on the Aisne. The obvious difficulties of the Germans on the Ancre front, made it important to prevent the Germans from withdrawing to the new defences being built behind the Noyon salient (eventually known as the Hindenburg Line/Siegfriedstellung) in their own time. A retirement could disrupt the British offensive at Arras and Franco-British planning gained urgency as a German withdrawal became likely in February and March, according to the results of air reconnaissance, agent reports and gleanings from prisoners.
Reaching a good position for an attack on the Bihucourt line (Riegel II Stellung) which ran from Ablainzevelle to west of Logeast Wood, west of Achiet le Grand, western outskirts of Bapaume, Rocquigny, le Mesnil en Arrousaise to Vaux Wood, the Fifth Army objective was to be attacked three days before the Arras offensive and the army then to advance to St Léger, to meet the Third Army and trap the Germans in their positions south-west of Arras. The first stage was to be an attack on 17 February, in which II Corps was to capture Hill 130. Gird Trench and the Butte de Warlencourt was to be captured by I Anzac Corps on 1 March and Serre was to be taken by V Corps on 7 March, which would then extend its right flank to the Ancre, to relieve the 63rd (Royal Naval) Division of II Corps and capture Miraumont by 10 March. These operations would lead to the attack on the Bihucourt line by II Corps and I Anzac Corps. These arrangements were maintained until 24 February, when German local withdrawals in the Ancre valley, required the Fifth Army divisions to make a general advance to regain contact.
Prelude
51st (Highland) Division
The state of the ground on the Somme front became much worse in November 1916, when constant rain fell and the ground which had been churned by shellfire since June, turned to deep mud again. (Some witnesses considered that the state of the ground was worse than at Ypres a year later.) The ground in the Ancre valley was in the worst condition, a wilderness of mud, flooded trenches, shell-hole posts, corpses and broken equipment, overlooked and vulnerable to sniping from German positions. Little could be done beyond holding the line and frequently relieving troops, who found the physical and mental strain almost unbearable. Supplies had to be moved up by soldiers at night, to avoid sniping by German infantry and artillery-fire. Horses in transport units were used as pack animals and died when the oat ration was reduced to 6 lb (2.7 kg) per day. In January the weather slightly improved and on 14 January, the temperature fell enough to freeze the ground.
On the south side of the Ancre valley near Courcelette, the 51st (Highland) Division took over from the 4th Canadian Division on 27 November. The division had only just been relieved from the line on the north bank, after the Battle of the Ancre (13–18 November 1916) with very little time for rest. Constant rain wet the ground so badly, that horses drowned and men became stuck up to their waists; in December ropes were issued to drag soldiers out of the mud. New trenches collapsed as they were dug and the front and support lines were held by shell-hole posts, which became islands of squalor. Duckboards and ration boxes used as platforms sank under the mud; cooking became impossible and movement in daylight suicidal. There were epidemics of dysentery, trench foot and frostbite; old wounds opened. Morale plummeted and moving about after dark led to working parties, runners, reliefs and ration parties getting lost and wandering around until exhausted. No man's land was not wired on this part of the front and British and German troops blundered into the wrong positions, Germans being taken prisoner on six occasions. Some dug-outs in Regina Trench were usable but conditions in the artillery lines were as bad as the front line, with ammunition being delivered by pack horse under German artillery fire. "Elephant" shelters (the materials for which took ten men to carry forward and 24 hours to build) were placed in the front-line, sunk below trench and shell-hole parapets. Larger shelters were dug into the sides of roads further back and only a minimal number of troops kept in the front zone.
After three weeks' work, positions in the front line had been improved and a frost hardened the ground, then a thaw made the ground worse than before. The 51st (Highland) Division stores obtained enough gumboots for an infantry brigade but many were lost in the mud as men struggled to get free. The division wore highland kilts, which left the top of the leg bare underneath and their boot edges chafed the skin and caused septic sores, until 6,000 pairs of trousers were issued. Wearing the boots and standing for long periods made men's feet swell and walking became almost impossible. Buses were brought up to Pozières to collect soldiers as they straggled back from the front line during a relief. Food containers proved too heavy to carry the 2,000 yd (1.1 mi; 1.8 km) to the front line and were replaced by Tommy cookers, which were cans of solidified alcohol to heat tinned food. Quartermasters improvised large numbers of extra cookers, so that the troops in the line could eat hot food when they pleased but the improvements made little difference to sickness. The division began to relieve battalions after 48 hours, with 24 hours' rest before and after each period in the line. On 11 December, the divisional front was reduced to two battalions, with the front of each battalion area being held by a company and two Lewis-gun crews. Company strengths had declined to 50–60 men, so thinly spread that a stray German was taken prisoner near a brigade headquarters, having seen no sign of British troops until he was captured. In December and January, the division suffered 439 casualties to enemy action, far fewer than those due to the weather and illness; the division was relieved by the 2nd Division on 12 January.
2nd Division
The 2nd Division, also transferred from the north side of the Ancre valley, took over from the Highlanders on 13 January, on a front of 2,500 yd (1.4 mi; 2.3 km), 1,200 yd (1,100 m) south of the village of Pys. The front line consisted of 18 infantry posts and support positions held by ten platoons, with nothing until three platoons in Courcelette and two companies nearby. Ironside Avenue, a communication trench, ran forward 800 yd (730 m) towards the front line but it was full of mud and impassable. Brushwood tracks, unusable during the day, continued the route towards the front line. Two battalions took over the front posts, with two more back towards Ovillers and La Boisselle, with the 15th (Scottish) Division on the right and the 18th (Eastern) Division on the left. The 2nd Division continued to consolidate the positions begun earlier, large working parties labouring non-stop to dig out, clean and pump trenches, fit duckboards and provide overhead cover for the infantry posts; tramways were built further back by engineers. Both sides were quiet during the rest of January, until the Germans attempted a raid which was stopped by machine-gun fire before the raiders had advanced past the German barbed wire; on the north side of the valley, British troops captured the rest of the Beaumont Hamel spur. By the end of the month conditions were better, although snowstorms covered the few landmarks and relieving parties frequently got lost. There was little artillery fire in the divisional areas but much German aircraft activity; British reconnaissance aircraft managed to photograph the front line on 29 January, giving the divisional commander the first accurate information about it. The freeze lasted for about five weeks until mid-February, which made movement of carrying-parties much easier as preparations to attack were being made.