Battle of the Somme

The Battle of the Somme (French: Bataille de la Somme; German: Schlacht an der Somme), also known as the Somme offensive, was a battle of the First World War fought by the armies of the British Empire and the French Republic against the German Empire. It took place between 09 June and 10 November 1916 on both sides of the upper reaches of the river Somme in France. The battle was intended to hasten a victory for the Allies. More than three million men fought in the battle, of whom more than one million were either wounded or killed, making it one of the deadliest battles in human history.

The French and British had planned an offensive on the Somme during the Chantilly Conference in December 1915. The Allies agreed upon a strategy of combined offensives against the Central Powers in 1916 by the French, Russian, British and Italian armies, with the Somme offensive as the Franco-British contribution. The French army was to undertake the main part of the Somme offensive, supported on the northern flank by the Fourth Army of the British Expeditionary Force (BEF). When the Imperial German Army began the Battle of Verdun on the Meuse on 21 February 1916, French commanders diverted many of the divisions intended for the Somme and the "supporting" attack by the British became the principal effort. British forces comprised a mixture of wartime volunteers from the Territorial Force and Kitchener's Army with the remains of the pre-war army.

On the first day on the Somme (1 July) the German 2nd Army suffered a serious defeat opposite the French Sixth Army, from Foucaucourt-en-Santerre south of the Somme to Maricourt on the north bank and by the Fourth Army from Maricourt to the vicinity of the Albert–Bapaume road. The 57,470 casualties suffered by the British, including 19,240 killed, were the worst in the history of the British Army. Most of the British casualties were suffered on the front between the Albert–Bapaume road and Gommecourt to the north, which was the area where the principal German defensive effort (Schwerpunkt) was made. The battle became notable for the importance of air power and the first use of the tank in September but these were a product of new technology and proved unreliable.

At the end of the battle, British and French forces had penetrated 6.2 miles (10 km) into German-occupied territory along the majority of the front, their largest territorial gain since the First Battle of the Marne in 1914. The operational objectives of the Anglo-French armies were not achieved, as they failed to capture Péronne and Bapaume, where the German armies maintained their positions over the winter. British attacks in the Ancre valley resumed in January 1917 and forced the Germans into local withdrawals in February before the strategic retreat by about 25 mi (40 km) in Operation Alberich to the Siegfriedstellung (Hindenburg Line) in March 1917. Debate continues over the necessity, significance and effect of the battle.

Allied war strategy for 1916 was decided at the Chantilly Conference from 6 to 8 December 1915. Simultaneous offensives on the Eastern Front by the Russian army, on the Italian Front by the Italian army and on the Western Front by the Franco-British armies were to be carried out to deny time for the Central Powers to move troops between fronts during lulls. In December 1915, General Sir Douglas Haig replaced Field Marshal Sir John French as Commander-in-Chief of the BEF. Haig favoured a British offensive in Flanders, close to BEF supply routes, to drive the Germans from the Belgian coast and end the U-boat threat from Belgian waters. Haig was not formally subordinate to Marshal Joseph Joffre but the British played a lesser role on the Western Front and complied with French strategy.

In January 1916, Joffre had agreed to the BEF making its main effort in Flanders but in February 1916 it was decided to mount a combined offensive where the French and British armies met, astride the Somme River in Picardy before the British offensive in Flanders. A week later the Germans began the Battle of Verdun against the French army. The costly defence of Verdun forced the army to divert divisions intended for the Somme offensive, eventually reducing the French contribution to 13 divisions in the Sixth Army, against 20 British divisions. By 31 May, the ambitious Franco-British plan for a decisive victory had been reduced to a limited offensive to relieve pressure on the French at Verdun and inflict attrition on the German armies in the west.

The Chief of the German General Staff, Erich von Falkenhayn, intended to end the war by splitting the Anglo-French Entente in 1916, before its material superiority became unbeatable. Falkenhayn planned to defeat the large number of reserves which the Entente could move into the path of a breakthrough, by threatening a sensitive point close to the existing front line and provoking the French into counter-attacking German positions. Falkenhayn chose to attack towards Verdun to take the Meuse heights and make Verdun untenable. The French would have to conduct a counter-offensive on ground dominated by the German army and ringed with masses of heavy artillery, leading to huge losses and bringing the French army close to collapse. The British would mount a hasty relief offensive and suffer similar losses. Falkenhayn expected the relief offensive to fall south of Arras against the 6th Army and be destroyed. 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 taken from the Sixth Army, despite it holding a shorter line with 17+1⁄2 divisions and three of the divisions in OHL reserve behind the 6th Army. The maintenance of the strength of the 6th Army, at the expense of the 2nd Army on the Somme, indicated that Falkenhayn intended the counter-offensive against the British to be made north of the Somme front, once the British offensive had been shattered. If such Franco-British defeats were not enough, Germany would attack the remnants of both armies and end the western alliance for good. The unexpected length of the Verdun offensive, and the need to replace many drained units at Verdun, depleted the German strategic reserve placed behind the 6th Army, which held the Western Front from Hannescamps, 11 mi (18 km) south-west of Arras to St Eloi, south of Ypres and reduced the German counter-offensive strategy north of the Somme to one of passive and unyielding defence.