Editing First day on the Somme (section)

===Tactical developments===

====French====
The offensives of 1915 showed that attacks would inevitably be slow and costly; on 8 January 1916, GQG issued "{{lang|fr|Instruction sur le combat offensif des petits unités}}" ("Instructions on Small Unit Offensive Operations") and "{{lang|fr|Instruction sur le combat offensif des grandes unités}}" on 26 January ("Instructions on large Unit Offensive Operations"). On 20 April, General [[Ferdinand Foch]], commander of {{lang|fr|Groupe d'armées du Nord}} (GAN, [[Army Group North (France)|Northern Army Group]]) issued "{{lang|fr|L'Instruction du Général Commandant du GAN sur le battaille offensif}}" ("The GAN Commander's Instruction on Offensive Battle") an {{nowrap|82-page}} pamphlet on the stages and processes of an attack on enemy positions prepared in depth.{{sfn|Gale|2018|p=293}} The pamphlet was a substantial revision of {{lang|fr|Note 5779}}, derived from "{{lang|fr|But et conditions d'une action offensive d'ensemble"}} (''Purpose and Conditions of Comprehensive Offensive Action'' 16 April 1915), a manual compiled from analysis of the fighting in 1914 and the basis of French offensive planning in 1915. Battle would now be methodical until the power of resistance of the defender was broken by "moral, material and physical degradation", while the attacker retained the ability to continue the offensive; a breakthrough was unlikely but not ruled out.{{sfn|Krause|2013|pp=4–5, 20}} Co-ordination of artillery and infantry was fundamental to the process, in which artillery would destroy defences and then infantry would occupy them, infantry objectives being determined by the capacity of artillery to prepare the way and limit casualties.{{sfn|Philpott|2009|pp=145–146}}

Artillery bombardments were to be co-ordinated with infantry attacks, various types of artillery being given targets suitable for their characteristics, for the cumulative destruction of field defences and the killing of German infantry. Heavy artillery and mortars were to be used for the destruction of field fortifications, howitzers and light mortars for the destruction of trenches, machine-gun and observation posts; heavy guns and mortars to destroy fortified villages and concrete strong points. Longer-range guns were to engage German artillery with counter-battery fire, to deprive German infantry of artillery support during the attack, when French infantry were at their most vulnerable. Wire cutting was to be performed by field artillery, firing [[high-explosive]] (HE) shells and supported by specialist wire-cutting sections of infantry, which would go out the night before an attack. During the attack, the field artillery would fire a linear barrage on trenches and the edges of woods and villages. Infantry tactics were to be based on reconnaissance, clear objectives, liaison with flanking units and the avoidance of disorganisation within attacking units. General attacks would need to be followed by the systematic capture of remaining defences to obtain jumping-off positions for the next general attack.{{sfn|Philpott|2009|pp=146–148}}

====British====
[[File:Lewis Gun (derivated).jpg|left|thumb|{{centre|An example of a [[Lewis gun]]}}]]
In 1915, British tactical thinking had been based on the experience of its [[Western Front (World War I)|Western Front]] battles, particularly the [[Battle of Loos]] in September and the study of French and German experience in translated manuals and pamphlets. British planners knew the importance of organised artillery firepower and the integration of types of weapons and equipment. [[Barrage (artillery)|Creeping barrages]], [[smoke screen]]s and [[Chemical warfare|cloud gas discharges]] were to be used along with aircraft, [[Stokes mortar]]s (a light trench mortar), [[Lewis gun]]s (a light machine-gun) and elaborate signals systems to counter the chronic lack of communication, once infantry advanced beyond their telephone system when they attacked. Troops were to advance in a succession of lines grouped into waves, followed by parties to consolidate captured ground or pass through the leading troops and continue the advance.{{sfn|Griffith|1996|pp=53–54}}

The [[9th (Scottish) Division]] had attacked at Loos with four battalions on a front {{cvt|1600|yd}} wide, each battalion in three waves. A second battalion followed each of the leading battalions in the same formation, ready to [[Leapfrogging (infantry)|leapfrog]] beyond and a second brigade followed the first as a reserve. Six lines of infantry, with the soldiers {{cvt|2|yd}} apart had confronted the German defence. Lines and waves had been made thinner and shallower since then. On 14 July 1916, in the attack on Longueval, the 9th (Scottish) Division advanced with four battalions. Companies were arranged in columns of platoons, creating four platoon waves {{cvt|70|yd}} apart. One of the attacking brigades advanced with each battalion on a two-company front with two companies behind and a second battalion following on. Each section of the front was attacked by sixteen platoon waves. Six platoons had attacked on a front of about {{cvt|1000|yd}}, roughly one soldier every {{cvt|5.5|yd}}.{{sfn|Griffith|1996|pp=53–54}}

====German====
On the Somme front, the construction plan ordered by Falkenhayn in January 1915 had been completed. [[Barbed wire]] obstacles had been enlarged from one belt {{cvt|5|–|10|yd}} deep to two belts {{cvt|30|yd}} deep and about {{cvt|15|yd}} apart. Double and triple thickness wire was used and laid {{cvt|3|–|5|ft}} high. The front line had been increased from one trench to three, dug {{cvt|150|–|200|yd}} apart, to create a front position, the first trench ({{lang|de|Kampfgraben}}, fighting or battle trench) occupied by sentry groups, the second ({{lang|de|Wohngraben}}, accommodation trench) for the front-trench garrison and the third trench for local reserves. The trenches were [[Traverse (trench warfare)|traversed]] and had sentry-posts in concrete recesses built into the parapet. Dugouts had been deepened from {{cvt|6|–|9|ft}} to {{cvt|20|–|30|ft}}, {{cvt|50|yd}} apart and large enough for {{nowrap|25 men.}} An intermediate line of strongpoints ({{lang|de|Stützpunktlinie}}) about {{cvt|1000|yd}} behind the front position, wired for all-round defence, had also been built. Communication trenches ran back to the reserve lines, renamed the second position, which was as well built and wired as the first position. The second position was beyond the range of Allied field artillery, to force an attacker to stop an advance for long enough to move artillery forward.{{sfn|Wynne|1976|pp=100–101}}