The Second Battle of the Aisne (Bataille du Chemin des Dames or Seconde bataille de l'Aisne, 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 80 km (50 mi), east–west ridge of the Chemin des Dames, 110 km (68 mi) 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 Groupe d'armées de Reserve (GAR, Reserve Army Group) attacked the Chemin des Dames and the next day, the Fourth Army, part of Groupe d'armées de Centre (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 c. 29,000 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 Nivelle was superseded by General Philippe Pétain, who adopted a strategy of "healing and defence", to resume the wearing-out of the German Army while conserving French infantry.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 40–62 mutineers 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 (31 July – 10 November) and the Battle of Cambrai (20 November – 8 December). 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.

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 24 to 48 hours. 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 c. 1.2 million troops and 7,000 guns 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 40 km (25 mi) deep in front of the French positions facing east from Soissons, northwards to St. Quentin. Alberich freed 13 to 14 German divisions, which were moved to the Aisne, increasing the German garrison to 38 divisions against 53 French divisions. The German withdrawal forestalled the attacks of the British and Groupe d'armées du Nord (GAN) but also freed French divisions for the attack. By late March, GAN had been reduced by eleven infantry, two cavalry divisions and 50 heavy guns, which went into the French strategic reserve.

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 (Grundsätze für die Führung in der Abwehrschlacht) 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 (Allgemeines über Stellungsbau).

Experience of the German First Army in the Somme Battles, (Erfahrungen der I. Armee in der Sommeschlacht) 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 (Ablösungsdivisionen). 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 (Gegenstoß) 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 (Gegenangriff) after 24 to 48 hours by the relief divisions. Ludendorff was sufficiently impressed by the Loßberg memorandum to add it to the new Manual of Infantry Training for War.