The British attacks at Festubert forced the Germans back 1.9 mi (3 km) and diverted reserves from the French but the Tenth Army gained little more ground, despite firing double the amount of artillery ammunition and many more casualties on both sides.

The French had regained 6.2 sq mi (16 km2) of territory but their failure to capture Vimy Ridge, despite the expenditure of 2,155,862 shells and the suffering of 102,500 casualties, led to recriminations against Joffre.

Joffre retained undivided command and freedom to conduct operations as he saw fit, which had been given at the beginning of the war but was instructed to consult with his subordinates; provisional army groups, which had been established in late 1914, were made permanent soon afterwards.

[6] In memoranda issued on 7 and 25 January 1915, Falkenhayn ordered that the positions of the German armies in France were to be fortified to resist attacks with only small forces, to enable reserves to be sent to Russia.

On 30 March, its Chief of Staff, Colonel Hans von Seeckt, recommended an offensive between Arras and Albert, requiring fourteen corps and 150 heavy artillery batteries.

An offensive in the west was cancelled in April, due to the deteriorating situation on the Eastern Front, where the Austro-Hungarian Army (Landstreitkräfte Österreich-Ungarns/Császári és Királyi Hadsereg) faced collapse.

West of Lille, the front line was in the marshy Flanders plain and south of La Bassée, the ground was criss-crossed by waterways and drainage ditches, which made fortification difficult.

[18] At every 100 yd (91 m), a machine-gun nest had been built into the trench and small, fortified posts supported the defenders, one to the north-east of the Chapel of Notre Dame de Lorette, with dug-outs over 50 ft (15 m) deep.

[28] In the XXXIII Corps area, the Division Marocaine (DM) attacked with two waves of "shock troops", who were lightly-equipped and pushed forward as quickly as possible, leaving isolated German positions to the Nettoyeurs (cleaners) following them.

[29] The 77th Division reached Givenchy-en-Gohelle, the cemetery at Souchez, Château de Carleul and took c. 500 prisoners and thirty machine-guns but was soon forced back to the Souchez–Neuville road, by German artillery-fire and counter-attacks.

[30] The 39th Division crossed the German trenches in front of La Targette, where two strong points contained artillery but the French advance was so swift, that only a few machine-gunners were able to engage them and the village was captured by 11:15 a.m., 350 prisoners being taken.

On 23 May the XXI Corps captured the rest of the Lorette Spur and on 27 May the 70th Division took Ablain cemetery, then the sugar refinery on 31 May, which made Souchez vulnerable to an attack from the west as well as the south.

[45] An attempt to return to larger combined attacks by IX, XXI and XXXIII corps from 25 to 26 May failed in most places, because of increases in the capability of the German defence, the impossibility of obtaining surprise and a lack of time to plan operations or to rest troops.

The French attacked into the valley and on 31 May captured Mill Malon, advanced up a communication trench to the sugar refinery and rushed the German garrison, which was overwhelmed as dark fell.

[52] The British adopted siege warfare tactics of limited attacks prepared by a greater weight of artillery fire, to capture more ground and hold it with fewer casualties.

[53] On 16 May Haig resumed the offensive with the Battle of Festubert, which was fought on the right flank of the Aubers Ridge battlefield, where British troops were ordered to press on to local objectives only after consolidating.

[60] IX, XX and XXXIII corps used 10,000 shells, which contained poison gas and incendiary material on Neuville, Souchez and Angres, German artillery positions at ferme La Folie and rear areas.

[64] In the Second Action of Givenchy (15–16 June), IV Corps of the British First Army, attacked north-west of La Bassée with the 7th, 51st and Canadian divisions after a 60-hour bombardment, in which an attempt to alleviate an acute ammunition shortage was made by relying on artillery observation and tactical reconnaissance by reinforced RFC squadrons.

[71] In the I Bavarian Reserve Corps area (General Karl von Fasbender), the 5th Bavarian Reserve Division (General Kress von Kressenstein) south of Carency, was pushed back to a line from Cabaret Rouge to Neuville St Vaast (Neuville) and French troops advanced as far as artillery positions around Givenchy-en-Gohelle (Givenchy), where reinforcements arrived at noon and managed to forestall a new French attack.

To avoid a retirement, which would lead to the loss of the Lorette Spur, Rupprecht met the corps commanders and issued a standfast order, encouraged by the quietude of the French during the morning of 11 May.

[79] Late on 12 May Rupprecht created Armee–Gruppe Fasbender to control the units in the areas of the XIV and I Bavarian Reserve corps, to hold the existing positions and establish a defence line from Carency and Neuville.

Constant French attacks slowly forced the surviving defenders back but the consequences of losing ground north-west of Souchez were so dangerous, that a stream of German units were sent to hold the area between late May and 7 June.

[73] From 9 to 12 May the Tenth Army made the largest advance since trench warfare began, using the new tactics which caused the German defenders great difficulty, even on the flanks where the attacks were repulsed.

[109] Foch wrote a report in early August in which he explained that the failure to hold Hill 145 was due to XXXIII Corps and the Tenth Army reserves being too distant and not deployed according to a proper reinforcement plan.

First-class French divisions had lost many experienced soldiers, which reduced them to mediocrity; the methods of Note 5779 had not been adopted consistently and became a greater problem when replacement troops with no experience, tried to continue the offensive.

[115] In September Foch wrote of the speed with which the Germans had moved reinforcements into the area from 9 to 18 May, dug new defensive lines and brought more heavy artillery into action, which from 18 May maintained barrages along the Tenth Army front.

André Laffargue, an artillery officer, was prompted to write Étude sur l'attaque dans le période actuelle de la guerre, an example of the trend to artillery-based tactics and infiltration by infantry.

[121] The apparent lost opportunity on 9 May, when Vimy Ridge was captured in the first rush, led the French army commanders to conclude that more of the same could achieve a breakthrough if better organised, which formed the basis of the planning for the autumn offensives in Artois and Champagne.

A flaw in Note 5779, was persistence with a concept of rapid breakthrough, even after many soldiers considered that the war had become a siege and that none of the French offensives of 1915, had been intended to return to mobile warfare.

[133] Changes made to the plan for the Second Battle of Artois, had been intended to secure the capture Vimy Ridge as a jumping-off point, rather than to achieve a breakthrough and return to mobile warfare.