The Second Battle of the Aisne ( or , 16 April – mid-May 1917) was the main part of the Nivelle Offensive, a Franco-British attempt to inflict a decisive defeat on the German armies in France. The Entente strategy was to conduct offensives from north to south, beginning with an attack by the British Expeditionary Force (BEF) then the main attack by two French army groups on the Aisne. General Robert Nivelle planned the offensive in December 1916, after he replaced Joseph Joffre as Commander-in-Chief of the French Army.
The objective of the attack on the Aisne was to capture the prominent , east–west ridge of the Chemin des Dames, north-east of Paris and then advance northwards to capture the city of Laon. When the French armies met the British advancing from the Arras front, the Germans would be pursued towards Belgium and the German frontier. The offensive began on 9 April, when the British began the Battle of Arras. On 16 April, the (GAR, Reserve Army Group) attacked the Chemin des Dames and the next day, the Fourth Army, part of (GAC, Central Army Group), near Reims to the south-east, began the Battle of the Hills.
The Chemin des Dames ridge had been quarried for stone for centuries, leaving a warren of caves and tunnels which were used as shelters by German troops to escape the French bombardment. The offensive met massed German machine-gun and artillery fire, which inflicted many casualties and repulsed the French infantry at many points. The French achieved a substantial tactical success and took prisoners but failed to defeat decisively the German armies. The failure had a traumatic effect on the morale of the French army and many divisions mutinied. Nivelle was superseded by General Philippe Pétain, who adopted a strategy of "healing and defence", to resume the wearing-out of the German Army while conserving French infantry. Pétain began a substantial programme re-equipment of the French Army, had shot as scapegoats, provided better food, more pay and more leave, which led to a considerable improvement in morale.
The new French strategy was not one of passive defence; in June and July the Fourth, Sixth and Tenth Armies conducted several limited attacks and the First Army was sent to Flanders to participate in the Third Battle of Ypres. The British prolonged the Arras offensive into mid-May, despite uncertainty about French intentions, high losses and diminishing returns, as divisions were transferred northwards to Flanders. The British captured Messines Ridge on 7 June and spent the rest of the year on the offensive at Ypres () and the Battle of Cambrai (). The mutinies in the French armies became known to the Germans but the cost of the defensive success on the Aisne made it impossible to reinforce Flanders and conduct more than local operations on the Aisne and in Champagne. A French attack at Verdun in August completed the recapture of much of the ground lost in 1916. The Battle of La Malmaison in October captured the west end of the Chemin des Dames and forced the Germans to withdraw to the north bank of the Ailette.
Background Strategic developments
Nivelle believed the Germans had been exhausted by the Battle of Verdun and the Battle of the Somme in 1916 and could not resist a breakthrough offensive, which could be completed in The main attack on the Aisne would be preceded by a large diversionary attack by the British Third and First armies at Arras. The French War Minister, Hubert Lyautey and Chief of Staff General Philippe Pétain opposed the plan, believing it to be premature. The British Commander-in-Chief, Sir Douglas Haig, supported the concept of a decisive battle but insisted that if the first two phases of the Nivelle scheme were unsuccessful, the British effort would be moved north to Flanders. Nivelle threatened to resign if the offensive did not go ahead and having not lost a battle, had the enthusiastic support of the British Prime Minister David Lloyd George. The French Prime Minister Aristide Briand supported Nivelle but the war minister Lyautey resigned during a dispute with the Chamber of Deputies and the Briand government fell; a new government under Alexandre Ribot took office on 20 March.
The Second Battle of the Aisne involved troops and on a front from Reims to Roye, with the main effort against the German positions along the Aisne river. The plan of December 1916 was plagued by delays and information leaks. By the time the offensive began in April 1917, the Germans had received intelligence of the Allied plan and strengthened their defences on the Aisne front. The German retreat to the Hindenburg Line, Operation Alberich (Unternehmen Alberich) left a belt of devastated ground up to deep in front of the French positions facing east from Soissons, northwards to St. Quentin. freed divisions, which were moved to the Aisne, increasing the German garrison to against divisions. The German withdrawal forestalled the attacks of the British and (GAN) but also freed French divisions for the attack. By late March, GAN had been reduced by eleven infantry, two cavalry divisions and guns, which went into the French strategic reserve.
Tactical developments
When Hindenburg and Ludendorff took over from Falkenhayn on 28 August 1916, the pressure being placed on the German army in France was so great that new defensive arrangements, based on the principles of depth, invisibility and immediate counter-action were formally adopted, as the only means by which the growing material strength of the French and British armies could be countered. Instead of fighting the defensive battle in the front line or from shell-hole positions near it, the main fight was to take place behind the front line, out of view and out of range of enemy field artillery. Conduct of the Defensive Battle () was published on 1 December 1916. The new manual laid down the organisation for the mobile defence of an area, rather than the rigid defence of a trench line. Positions necessary for the new method were defined in Principles of Field Position Construction ().
Experience of the German First Army in the Somme Battles, () was published on 30 January 1917. Towards the end of 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 (). In his analysis of the battle, Loßberg opposed the granting of discretion to front trench garrisons to retire, as he believed that manoeuvre did not allow the garrisons to evade Allied artillery-fire, which could blanket the forward area and invited enemy infantry to occupy vacated areas unopposed. Loßberg considered that spontaneous withdrawals would disrupt the counter-attack reserves as they deployed and further deprive battalion and division commanders of the ability to conduct an organised defence, which the dispersal of infantry over a wider area had already made difficult. Loßberg and other officers 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 and wanted the Somme practice of fighting in the front line to be retained and authority devolved no further than the battalion, so as to maintain organisational coherence, in anticipation of a methodical counter-attack () after by the relief divisions. Ludendorff was sufficiently impressed by the Loßberg memorandum to add it to the new Manual of Infantry Training for War.
Prelude German defensive preparations
During the German withdrawal to the (Hindenburg Line) in March 1917, a modest withdrawal took place in the neighbourhood of Soissons. On 17 March, the German defences at Crouy and were found to be empty and as French troops followed up the retirement, German troops counter-attacked at Vregny and Margival, which reduced the speed of the French pursuit to a step-by-step advance. By April, the French advance had only progressed beyond Neuville-sur-Margival and Leuilly. On 1 April, a French attack along the line of the Ailette–Laon road reached the outskirts of Laffaux and Vauxaillon. Vauxeny and Vauxaillon were occupied a few days later.
Defensive battle
In a new manual of 1 December 1916, (Principles of Command for Defensive Battle), 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 (battle zone), a second defensive area deep, also placed as far as possible on ground hidden from enemy observation, while remaining in view of German artillery observers. A (rear battle zone) further back was to be occupied by the reserve battalion of each regiment.
Field fortification
"Principles of Field Fortification" () was published 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 greater numbers of men. 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 Allies' growing 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, (). If the immediate counter-attack failed, the (counter-attack) divisions would take their time to prepare a methodical attack, provided 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 .
Battle Third Army