Battle of the Somme

In the spring allied commanders had been concerned about the ability of the French army to withstand the enormous losses at Verdun. The original plans for an attack around the river Somme were modified to let the British make the main effort. This would serve to relieve pressure on the French, as well as the Russians who had also suffered great losses. On 1 July, after a week of heavy rain, British divisions in Picardy launched an attack around the river Somme, supported by five French divisions on their right flank. The attack had been preceded by seven days of heavy artillery bombardment. The experienced French forces were successful in advancing but the British artillery cover neither blasted away barbed wire, nor destroyed German trenches. They suffered the greatest number of casualties in a single day in the history of the British army, about 57,000.

Having assessed the air combat over Verdun, the Allies had new aircraft for the attack in the Somme valley. The Verdun lesson learnt, the Allies' tactical aim became the achievement of air superiority and the German planes were indeed, largely swept from the skies over the Somme. The success of the Allied air offensive caused a reorganization of the German air arm, and both sides began using large formations of aircraft rather than relying on individual combat

After regrouping, the battle continued throughout July and August, with some success for the British despite the reinforcement of the German lines. By August General Haig had concluded that a breakthrough was unlikely, and instead switched tactics to a series of small unit actions. The effect was to straighten out the front line, which was thought necessary in preparation for a massive artillery bombardment with a major push.

The final phase of the battle of the Somme saw the first use of the tank on the battlefield. The Allies prepared an attack that would involve 13 British and Imperial divisions and four French corps. The attack made early progress, advancing 3.2–4.1 km (35–4500) yards in places, but the tanks had little effect due to their lack of numbers and mechanical unreliability. The final phase of the battle took place in October and early November, again producing limited gains with heavy loss of life. All told, the Somme battle had made penetrations of only five miles, and failed to reach the original objectives. The Allies had suffered over 600,000 casualties and the Germans over 460,000