After the war, Sir William Robertson, Chief of the Imperial General Staff, explained what this strategy was:

Remembering the dissatisfaction by ministers at the end of 1915, because the operations had not come up to their expectations, the General Staff took the precaution to make quite clear beforehand the nature of success which the Somme campaign might yield. The necessity of relieving pressure on the French Army at Verdun remains, and is more urgent than ever. This is, therefore, the first objective to be obtained by the combined British and French offensive. The second objective is to inflict as heavy losses as possible upon the German armies.

The use of artillery was heavily supported by Field Marshall Haig:

The enemy’s position to be attacked was of a very considerable character, situated on high, undulating tract of ground. (They had) deep trenches….bomb proof shelters……wire entanglements forty yards broad often as thick as a man’s finger. Defences of this nature could only be attacked with the prospect of success after careful artillery preparation