Order of battle for the Battle of the Somme

This is the order of battle for the Battle of the Somme. The Battle of the Somme was an offensive fought on the Western Front during World War I from 1 July to 18 November 1916 as one of the greatest engagements of the war. It was fought between French, British and Dominion forces and the German Empire in the Somme River valley and vicinity in northern France.
Background.
British and Dominion forces.
In typical British county regiments, the 1st and 2nd Battalions were regular army, the 3rd was the special reserve battalion which did not normally serve overseas but remained at home as the regimental depot and training unit from which replacements were sent to the regular battalions. The 4th, 5th and 6th Battalions were normally Territorial Force battalions. Territorial battalions raised second line battalions which would be numbered 2/4th, 2/5th and 2/6th, initially from men who did not volunteer for overseas service. The terms of service in the Territorial Force meant that men who had signed up on these could not be forced to serve outside the United Kingdom. The number of battalions depended on the recruitment potential of the area from which the battalions were raised (i.e. the Dorsetshire Regiment raised eleven battalions, whilst the London Regiment managed to raise eighty-eight battalions).
Regular Army Divisions were numbered 1st to 8th. "New Army" divisions of Kitchener's Army raised after the outbreak of war were numbered 9th to 26th. The 27th to 29th Divisions were Regular Army divisions made up from units recalled from Imperial Garrison Duties. The 30th to 41st were again made up from New Army units while the 42nd to 74th were Territorial. The 63rd Division (Royal Naval Division) was made up from Naval Reserves and did not follow this numbering pattern.
Army and Corps organisation.
Corps.
French Sixth Army, which contained British or Dominion forces:
Formations per battle.
Refer following section titled "Divisions" for brigades, regiments and battalions associated with each division participating in the listed battles. Battle nomenclature and participating units information taken from source British Army Council Command Notice 1138 unless stated.
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French forces.
A majority of the French Divisions were triangular divisions – that is comprising three regiments, with each regiment containing three battalions.
During the Battle of Verdun, General Pétain had rotated the French Divisions through the battle – resulting in a large number of divisions entering the battle with experience.
Army and corps organisation.
List of Army/Corp/Divisions involved taken from "Organigramme des Grandes Batailles".
German: 2nd Army.
German order of battle derived from "Hart, Appendix C" unless stated.<br>
Commander: Fritz von Below On 19 July, split into the 1st Army (opposite the British) and the 2nd Army, Commander: General der Artillerie Max von Gallwitz (opposite the French) with authority over the 1st Army as , this was not an army group, the term for which was <br>
Chief of the German General Staff: Erich Falkenhayn (until 28 August 1916), Paul von Hindenburg
German divisions were being converted from square to triangular, hence some had four infantry regiments, others had three.
Citations and references.
References.
Books
Websites