At the beginning of 1917, the British and French were still searching for a way to achieve a strategic breakthrough on the Western Front. The previous year had been marked by the costly success of the Anglo-French offensive astride the
River Somme, while the French had been unable to take the initiative because of intense German pressure at
Verdun until after August 1916. The battles consumed enormous quantities of resources while achieving virtually no strategic gains on the battlefield. The cost to Germany of containing the Anglo-French attacks had been enormous and given that the material preponderance of the Entente and its allies could only be expected to increase in 1917, Field Marshal
Paul von Hindenburg and General
Erich Ludendorff decided on a defensive strategy on the Western Front for that year. This impasse reinforced the French and British commanders' belief that to end the stalemate they needed a breakthrough; while this desire may have been the main impetus behind the offensive, the timing and location were influenced by political and tactical considerations.
Home fronts The mid-war years were momentous times. Governing politicians in Paris and London were under great pressure from the press, the people and their parliaments to win the war. Hundreds of thousands of casualties had been suffered at the battles of
Gallipoli, the
Somme and
Verdun, with little prospect of victory in sight. The British
Prime Minister,
H. H. Asquith, resigned in early December 1916 and was succeeded by
David Lloyd George. In France,
Prime Minister Aristide Briand, along with
Minister of Defence Hubert Lyautey were politically diminished and resigned in March 1917, following disagreements over the prospective
Nivelle Offensive. The United States was close to declaring war on Germany; American public opinion was growing increasingly incensed by U-boat attacks upon civilian shipping, which had begun with the sinking of in 1915 and culminated in the torpedoing of seven American merchantmen in early 1917. The
United States Congress declared war on
Imperial Germany on 6 April 1917 but it would be more than a year before a suitable army could be raised, trained and transported to France.
Strategy It was agreed in the London Convention of 16 January 1917, that the French assault on the Aisne would begin in mid-April and that the British would make a diversionary attack in the Arras sector approximately one week prior. The French, Russians and British intended to launch a joint spring offensive in 1917 but this strategy foundered in February when the
Russians announced that they could not meet their commitments. The spring offensive was reduced from attacks on the Eastern and Western fronts to a French assault along the
Aisne River. In March, the German army in the west (), withdrew to the
Hindenburg line in Operation Alberich, negating the tactical assumptions of the French plan. British and French troops followed up the German retreat into the old Noyon Salient up to the new German fortifications of the Hindenburg line () and French doubts over the wisdom of the offensive increased and the British were wary of proceeding, given the rapidly changing tactical situation. The new French commander-in-chief General
Robert Nivelle, the victor of Verdun, claimed that he could combine overwhelming artillery-fire and skilful infantry tactics to break through the Western front in 48 hours. Lloyd George, the Prime Minister since 7 December 1916, accepted the claims of Nivelle, that if the British launched a diversionary assault to draw German troops away from the Aisne sector, the French offensive could succeed.
Tactics: British Expeditionary Force at Wagonlieu, 8 April 1917 Three of the armies of the
British Expeditionary Force (BEF,
Field Marshal Sir Douglas Haig) were in the Arras sector, the
Fifth Army (General
Hubert Gough) in the south, the
Third Army (General
Edmund Allenby) in the centre and the
First Army (General
Henry Horne) in the north and the plan was devised by Allenby. The British used the lessons of the Somme and Verdun the previous year and planned to attack on an front, from Vimy Ridge in the north to
Neuville-Vitasse, south of the Scarpe river. The preliminary bombardment was planned to last about a week except for a much longer and heavier barrage at Vimy Ridge.
Division attack training In December 1916, the training manual replaced of 8 May 1916 and marked a significant step in the evolution of the BEF into a homogeneous force, well adapted to its role on the Western Front. The duties of army, corps and divisions in planning attacks were standardised. Armies were to devise the plan and the principles of the artillery component. Corps were to allot tasks to divisions, which would then select objectives and devise infantry plans subject to corps approval. Artillery planning was controlled by corps with consultation of divisions by the corps General Officer Commanding, Royal Artillery (GOCRA) which became the title of the officer at each level of command who devised the bombardment plan, which was coordinated with neighbouring corps artillery commanders by the army GOCRA. Specific parts of the bombardment were nominated by divisions, using their local knowledge and the results of air reconnaissance. The corps artillery commander was to co-ordinate counter-battery fire and the howitzer bombardment for zero hour. Corps controlled the
creeping barrage but divisions were given authority over extra batteries added to the barrage, which could be switched to other targets by the divisional commander and brigade commanders. provided the basis for the operational technique of the BEF for the rest of 1917.
Platoon attack training The training manual of February 1917 marked the end of attacks made by lines of infantry with a few detached specialists. The platoon was divided into a small headquarters and four sections, one with two trained grenade-throwers and assistants, the second with a Lewis gunner and nine assistants carrying of ammunition, the third section comprised a sniper, scout and nine riflemen and the fourth section had nine men with four rifle-grenade launchers. The rifle and hand-grenade sections were to advance in front of the Lewis-gun and rifle-grenade sections, in two waves or in
artillery formation, which covered an area wide and deep, with the four sections in a diamond pattern, the rifle section ahead, rifle grenade and bombing sections to the sides and the Lewis gun section behind, until resistance was met. German defenders were to be suppressed by fire from the Lewis-gun and rifle-grenade sections, while the riflemen and hand-grenade sections moved forward, preferably by infiltrating around the flanks of the resistance, to overwhelm the defenders from the rear. The changes in equipment, organisation and formation were elaborated in
The Normal Formation For the Attack of February 1917, which recommended that the leading troops should push on to the final objective, when only one or two were involved but that for a greater number of objectives, when artillery covering fire was available for the depth of the intended advance, fresh platoons should "leap-frog" through the leading platoons to the next objective. The new organisations and equipment gave the infantry platoon the capacity for fire and manoeuvre, even in the absence of adequate artillery support. To bring uniformity in adoption of the methods laid down in the revised manuals and others produced over the winter, Haig established a BEF Training Directorate in January 1917, to issue manuals and oversee training. and its companion manuals provided British infantry with "off-the-peg" tactics, devised from the experience of the Somme and from French Army operations, to go with new equipment made available by increasing British and Allied war production and better understanding of the organisation necessary to exploit it in battle.
Tactics: German army In a new manual published on 1 December 1916 by (OHL, supreme command of the German army), ("Principles of Command for Defensive Battles in Positional Warfare") the policy of unyielding defence of ground, regardless of its tactical value, was replaced by the defence of positions suitable for artillery observation and communication with the rear, where an attacking force would
"fight itself to a standstill and use up its resources while the defenders conserve[d] their strength". Defending infantry would fight in areas, with the front divisions in an outpost zone up to deep behind listening posts, with the main line of resistance placed on a reverse slope, in front of artillery observation posts, which were kept far enough back to retain observation over the outpost zone. Behind the main line of resistance was a (main battle zone), a second defensive area deep, on ground (as far as possible) hidden from enemy observation, yet in view of German artillery observers. A (rear battle zone) further back was to be occupied by the reserve battalion of each regiment. ("Principles of Field Fortification") was published by OHL in January 1917 and by April an outpost zone () held by sentries, had been built along the Western Front. Sentries could retreat to larger positions () held by (five men and an NCO per ), who would join the sentries to recapture sentry-posts by immediate counter-attack. Defensive procedures in the battle zone were similar but with bigger units. The front trench system was the sentry line for the battle zone garrison, which was allowed to move away from concentrations of enemy fire and then counter-attack to recover the battle and outpost zones; such withdrawals were envisaged as occurring on small parts of the battlefield which had been made untenable by Allied artillery fire, as the prelude to (immediate counter-attack within the position). Such a decentralised battle by large numbers of small infantry detachments would present the attacker with unforeseen obstructions. Resistance from troops equipped with automatic weapons, supported by observed artillery fire, would increase the further the advance progressed. A school was opened in January 1917 to teach infantry commanders the new methods. Given the growing Allied superiority in munitions and manpower, attackers might still penetrate to the second (artillery protection) line, leaving in their wake, German garrisons isolated in resistance nests () still inflicting losses and disorganisation on the attackers. As the attackers tried to capture the and dig in near the German second line, and of the counter-attack divisions would advance from the into the battle zone, in an immediate (counter-attack from the deep). If the immediate counter-attack failed, counter-attack divisions would take their time to prepare a methodical attack if the lost ground was essential to the retention of the main position. Such methods required large numbers of reserve divisions ready to move to the battlefront. The reserve was obtained by creating by internal reorganisation of the army, bringing divisions from the eastern front and by shortening the Western Front, in
Operation Alberich. By the spring of 1917, the German army in the west had a strategic reserve of
German 6th Army "Experience of the German 1st Army in the Somme Battles", () was published on 30 January 1917 by Ludendorff but the new defensive methods were controversial. During the Battle of the Somme in 1916 Colonel
Fritz von Loßberg (Chief of Staff of the
1st Army) had been able to establish a line of relief divisions (), with the reinforcements from Verdun, that had begun to arrive in greater numbers in September. In his analysis of the battle, Loßberg opposed the granting of discretion to front trench garrisons to retire, as he believed that manoeuvre would not evade Allied artillery fire, which could blanket the forward area and invited French or British infantry to occupy vacant areas. Loßberg considered that spontaneous withdrawals would disrupt the counter-attack reserves as they deployed and further deprive battalion and division commanders of the means to conduct an organised defence, which the dispersal of infantry over a wide area had already made difficult. Loßberg and others had severe doubts as to the ability of relief divisions to arrive on the battlefield in time to conduct an immediate counter-attack () from behind the battle zone. Sceptics wanted the tactic of fighting in the front line to continue, with authority devolved no further than to the battalion, to maintain organisational coherence in anticipation of a methodical counter-attack () by the relief divisions after Ludendorff was sufficiently impressed by Loßberg's memorandum to add it to the new "
Manual of Infantry Training for War". General
Ludwig von Falkenhausen, commander of the
6th Army arranged the infantry at Arras for the rigid defence of the front line, supported by methodical counter-attacks (), by the "relief" divisions () on the second or third day. Five were placed behind
Douai, away from the front line. The new Hindenburg line ended at Telegraph Hill between Neuville-Vitasse and Tilloy lez Mofflaines, from whence the original system of four lines apart, ran north to the
Neuville St Vaast–
Bailleul-aux-Cornailles road. About behind were the
Wancourt–
Feuchy and to the north the Point du Jour lines, running from the
Scarpe river north along the east slope of
Vimy ridge. The new
Wotan line, which extended the Hindenburg position, was built around further back and not entirely mapped by the Allies until the battle had begun. Just before the battle, Falkenhausen had written that parts of the front line might be lost but the five could be brought forward to relieve the front divisions on the evening of the second day. On 6 April, General Karl von Nagel, the 6th Army chief of staff, accepted that some of the front divisions might need to be relieved on the first evening of battle but that any penetrations would be repulsed with local immediate counter-attacks () by the front divisions. On 7 April, Nagel viewed the imminent British attack as a limited effort against Vimy ridge, preparatory to a bigger attack later, perhaps combined with the French attack expected in mid-April. Construction of positions to fulfil the new policy of area defence had been drastically curtailed by shortages of labour and the long winter, which affected the setting of concrete. The 6th Army commanders had also been reluctant to encourage the British to change their plans if the British detected a thinning of the front line. The Germans were inhibited by the extent of British air reconnaissance, which observed new field works and promptly directed artillery fire on them. The 6th Army failed to redeploy its artillery, which remained in lines easy to see and bombard. Work on defences was also divided between maintaining the front line, strengthening the third line and the new (
Drocourt–Quéant switch line) further back. ==Prelude==