[1] The Battle of Arras of 1917 ended with the Germans in possession of a fortified wood to the west of the village of Oppy, which overlooked British positions.

The wood was 1 acre (0.4 ha) in area and contained many German observation posts, machine-gun nests and trench mortars.

Operations to continue the encirclement of Lens by an attack by the Canadian Corps on Hill 70 to the north were postponed until August due to a shortage of artillery.

A continuation of British attacks towards Cambrai would be pointless in the absence of French operations to the south and Field Marshal Sir Douglas Haig decided to continue operations on the Arras front to reach a good defensive line, then to conduct surprise attacks to keep German troops in the area.

[3] The move of the bulk of the British Expeditionary Force (BEF) to Flanders in late May and June, left the First Army with twelve divisions to hold a 34 mi (55 km) front from Arras northwards to Armentières on the Lys river.

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 (Ablösungsdivisionen), with the reinforcements from Verdun which had begun to arrive 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 did not allow the garrisons to evade Allied artillery fire, which could blanket the forward area, making evasion futile and also invite Allied troops 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 others had severe doubts as to the ability of relief divisions to reach the battlefield in time to conduct an immediate counter-attack (Gegenstoß) from behind the battle zone.

Loßberg wanted the Somme practice of fighting in the front line to be retained and authority devolved no further than the battalion, to maintain organisational coherence, in anticipation of a methodical counter-attack (Gegenangriff) by the relief divisions after 24–48 hours.

Erich Ludendorff, the Generalquartiermeister (First Quartermaster General) of the German armies was sufficiently impressed by the Loßberg memorandum to add it to the new Manual of Infantry Training for War.

[9] The new organisation and equipment gave the infantry platoon the capacity for fire and manoeuvre, even in the absence of adequate artillery support against German defences.

[12] The First Army plan had assumed a dawn attack and no preparations had been made for an advance at night, such as putting out boards with luminous paint on the German wire, taking compass-bearings or organising intermediate objectives.

Oppy Wood was full of fallen trees and tangled branches and a long west to east slope left the British field artillery at extreme range, which reduced its accuracy.

The raiders began to withdraw from Windmill Trench and stopped a German attempt to counter-attack around the northern flank, which was ambushed by a Lewis gun squad.

[20] On 3 April 1917, German Corps headquarters were detached from their component divisions and given permanent areas to hold under a geographical title.

Many of the troops were stranded in no man's land and had to wait all day under fire from snipers, machine-guns and artillery until nightfall, before completing the retirement.

[26] The composite brigade was bombarded as it moved forward to the assembly-positions, which caused many losses and delays in crowded communication trenches, some of the troops failed to reach the jumping-off positions in time.

On the "B" Battalion front, German troops bombed their way northwards and threatened the divisional junction with the 1st Canadian Division, which had captured Fresnoy.

[27] The day was dull and humid and at 5:30 p.m., German artillery bombarded the British jumping-off trenches for ten minutes and caused c. 200 casualties in the two attacking brigades.

Howitzers fired smoke-shell to create a screen, to the north of the 5th Division attack and then a thunderstorm began, the infantry advancing at 7:10 a.m. amidst lightning and torrential rain.

On the 5th Division front, the German trenches were strongly held but the British arrived so quickly that few were able to resist, except on the left flank where the objective was further away.

The right flank brigade was delayed for a short time at Fresnoy Park, then found only a battlefield strewn with dead soldiers and abandoned equipment.

The southern brigade managed to push forward and then bomb northwards to roll up the British front but despite rapid success, the division suffered 1,585 casualties.

[30] Losses of British corps aircraft declined after April, which had been the worst in the war and air fighting returned to the German rear areas.

[31][c] An attack on German observation balloons was planned during the lull in infantry operations before May and the pilots practised flying at low altitude to exploit the cover of trees, dips in the ground and houses.

Bombardments from both sides and infantry attacks and counter-attacks, made the battlefield so chaotic that observers were not able to see clearly, except for those of 43 Squadron, who saw German troops massing opposite the XIII Corps front.

After dark, bombing continued on trains; three were hit by low-level attacks by the night-bombing specialists of 100 Squadron, along with railway junctions and Tourmignies airfield.

Most of Avion, Éleu-dit-Leauwette and the German defences on the east side of Hill 65, were captured by the 4th Canadian and 46th (North Midland) Division.

British and Canadian troops nearby were pushed back to the eastern fringe of Arleux and the 5th Division withdrew its left flank to the Arleux–Neuvireuil road.