The battle of the Somme had its genesis in late 1915, following the failure of the piecemeal Allied offensives that autumn. In November, Prime Minister Asquith and the French Prime Minister met and agreed that the Allies needed to work together more closely. Shortly afterwards, the newly appointed commander of the BEF, General Sir Douglas Haig, met the French Chief of General Staff, General Joffre, at the Chantilly Conference. The latter was very much the senior partner and despite Haig's insistence that his armies should not be tasked to mount attacks to wear down the Germans, the French general issued the following instruction:
' I have directed the General Commanding the Group of the Armies of the North to make a study of a powerful offensive south of the Somme … This study is part of a general plan drawn up for the French Armies as a whole and will permit me to determine the points against which our principal effort will be made in the coming spring …the French offensive would be greatly aided by a simultaneous offensive of the British forces between the Somme and Arras… it will be a considerable advantage to attack the enemy on a front where… activity… has been less than elsewhere.'
The original plan was for a joint attack on a front of forty-five miles, astride the Somme. To the north the British were to attack with up to twenty-five divisions, while south of the River, the French Sixth Army was to attack with thirty-nine divisions on a front of thirty miles. Operations on the Western Front would compliment offensives by the Italians and the Russians.
Delays in equipping, training and deploying the New Army divisions ruled out British attacks in spring 1916. This suited Haig who, at the beginning of his command, had not yet accepted that he would have to fight a war of attrition. His natural instinct was to believe that once fully prepared, he could break through the German line in a continuous, rolling attack and resume open warfare. However, such was the ferocity of the German attack on the French at Verdun on 21 February that 'the mincing machine of battle' had to be 'fed' by a constant supply of fresh French divisions. Consequently, by late spring 1916, Joffre's only wish was to relieve pressure on the French Army, who he believed were 'near breaking point'. By June, Joffre was demanding that the British attack as soon as possible but he could only spare sufficient French divisions to attack on an eight mile front astride the Somme. Consequently, the British were to lead the offensive with the twenty five divisions split between General Rawlinson's Fourth Army and Gough's Reserve Army. The initial British attack was to be mounted by thirteen infantry divisions, with two further divisions of General Allenby's Third Army mounting a diversionary attack on the German salient at Gommecourt to the north.
Despite the change of concept from a massive joint Anglo/French attack, confidence grew in the coming offensive, as 'the flower of British manhood' arrived on the Somme with the New Army divisions. Even the older and more experienced soldiers, who in most cases did not share what has been characterised as the 'naïve optimism' of the Kitchener Volunteers, were impressed by the quantity of manpower and material arriving at the front.
General Rawlinson, however, did not share in the growing confidence of his men. Nor did he share Field Marshal Haigs's expectation that a breakthrough could be achieved or exploited. Although Rawlinson accepted Haig's plans for the rolling capture of the enemy defensive systems but, as the only infantryman amongst the three army commanders involved, he expected to mount deliberate attacks on each successive enemy position.