The first day on the Somme (1 July 1916) was the beginning of the Battle of Albert (1–13 July) the name given by the British to the first two weeks of the Battle of the Somme (1 July–18 November) in the First World War. Nine corps of the French Sixth Army and the British Fourth and Third armies attacked the German 2nd Army (General Fritz von Below). The attack was from Foucaucourt south of the Somme, northwards across the Somme and the Ancre to Serre and Gommecourt, 2 mi (3.2 km) beyond, in the Third Army area. The objective of the attack was to capture the German first and second defensive positions from Serre south to the Albert–Bapaume road and the first position from the road south to Foucaucourt.
The German defence south of the road mostly collapsed and the French had complete success on both banks of the Somme, as did the British from Maricourt on the army boundary with the French northwards. XIII Corps took Montauban and reached all its objectives, XV Corps captured Mametz and isolated Fricourt. The III Corps attack on both sides of the Albert–Bapaume road was a disaster, making only a short advance south of La Boisselle, where the 34th Division suffered the most casualties of any Allied division on 1 July. Further north, X Corps captured part of the Leipzig Redoubt (an earthwork fortification), failed opposite Thiepval and had a great but temporary success on the left flank, where the German front line was overrun and Schwaben and Stuff redoubts captured by the 36th (Ulster) Division.
German counter-attacks during the afternoon recaptured most of the lost ground north of the Albert–Bapaume road and more British attacks against Thiepval were costly failures. On the north bank of the Ancre, the attack of VIII Corps was a costly failure, with large numbers of British troops being shot down in no man's land. The VII Corps diversion at Gommecourt was also costly, with only a partial and temporary advance south of the village. The German defeats, from Foucaucourt to the Albert–Bapaume road, left the German defence on the south bank incapable of resisting another attack; a substantial German retreat began from the Flaucourt plateau to the west bank of the Somme close to Péronne. North of the Somme in the British area, Fricourt was abandoned by the Germans overnight.
Several truces were observed to recover wounded from no man's land on the British front; the Third Army diversion at Gommecourt cost 6,758 casualties against 1,212 German and the combined casualty count with the Fourth Army reached 57,470, (19,240 of which had been fatal). The French Sixth Army suffered 1,590 casualties and the German 2nd Army suffered 10,000–12,000 casualties. Orders were issued to the Anglo-French armies to continue the offensive on 2 July; a German counter-attack on the north bank of the Somme by the 12th Division, intended for the night of 1/2 July, took until dawn on 2 July to begin and was destroyed by the French and British troops opposite. Since 1 July 1916, the British casualties on the First Day and the "meagre gains" have been a source of grief and controversy in Britain.
In July 1915, the French Commander in Chief Joseph Joffre held the first Allied conference at Chantilly. In December, a second conference agreed a strategy of simultaneous attacks by the French, Russian, British and Italian armies. The British theatre of operations was in northern France and Flanders but in February 1916, Haig accepted Joffre's plan for a combined attack astride the Somme river, around 1 July; in April, the British Cabinet agreed to an offensive in France. The nature of a joint offensive on the Somme began to change almost immediately, when the German army attacked Verdun on 21 February. In March, Foch proposed a Somme offensive on a 28 mi (45 km) front, between Lassigny and the Somme with 42 French divisions and a British attack on a 16 mi (25 km) front from the Somme to Thiepval with 25 divisions. French divisions intended for the joint offensive were soon diverted to Verdun and the offensive was eventually reduced to a main effort by the British and a supporting attack by the French Sixth Army.
The Somme was to be the first mass offensive mounted by the British Expeditionary Force (BEF) and the first battle to involve a large number of New Army divisions, many composed of Pals battalions that had formed after Kitchener's call for volunteers in August 1914. By the end of the Gallipoli Campaign, twelve British divisions were in Egypt and from 4 February to 20 June, nine were transferred to France. From Britain and Egypt the 34th Division and 35th Division arrived in January, the 31st Division and the 46th (North Midland) Division in February, the 29th Division, 39th Division, 1st Australian Division and 2nd Australian Division in March, the New Zealand Division in April, the 41st Division, 61st (2nd South Midland) Division and 63rd (2nd Northumbrian) Division in May, the 40th Division, 60th (2/2nd London), 4th Australian and 5th Australian divisions in June and the 11th (Northern) Division on 3 July. The 55th (West Lancashire) Division and 56th (1/1st London) Division were reassembled, a battalion of the Newfoundland Regiment and the South African Brigade joined in April, followed by a contingent of the Bermuda Volunteer Rifle Corps in July.
Despite considerable debate among German staff officers, General Erich von Falkenhayn, the head of Oberste Heeresleitung (OHL, the supreme command of the German Army) insisted on a tactic of rigid defence of the front line in 1916 and implied after the war that the psychology of German soldiers, shortage of manpower and lack of reserves made the policy inescapable, since the troops necessary to seal off breakthroughs did not exist. High losses incurred in holding ground by a policy of no retreat were preferable to higher losses, voluntary withdrawals and the effect of a belief that soldiers had discretion to avoid battle. When a more flexible policy was substituted later, discretion was still reserved to army commanders. Despite the certainty by mid-June of an Anglo-French attack on the Somme against the 2nd Army, Falkenhayn sent only four divisions, keeping eight in the western strategic reserve. No divisions were moved from the 6th Army, despite it holding a shorter line with 17+1⁄2 divisions and three of the divisions in OHL reserve being in the 6th Army area. The maintenance of the strength of the 6th Army at the expense of the 2nd Army on the Somme, indicated that Falkenhayn intended a counter-offensive against the British to be made closer to Arras north of the Somme front, once the British offensive had been shattered.
The offensives of 1915 showed that attacks would inevitably be slow and costly; on 8 January 1916, GQG issued "Instruction sur le combat offensif des petites unités" ("Instructions on Small Unit Offensive Operations") and "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 Groupe d'armées du Nord (GAN, Northern Army Group) issued "L'Instruction du Général Commandant du GAN sur la bataille offensive" ("The GAN Commander's Instruction on Offensive Battle") an 82-page pamphlet on the stages and processes of an attack on enemy positions prepared in depth. The pamphlet was a substantial revision of Note 5779, derived from "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. 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.