The Somme was one of the key battles of the war. The date of the war actually started on July 1st 1916. British preliminary forces bombarded seven days earlier with a British 9.2 gun on the June 24th 1916. The bombardment went on for a week prior to the attack itself, with a total of 1500 guns firing more then 1 million rounds. They were hoping the surprise bombardment would destroy the German's barbed wire in front of the trenches. With the wire gone the British troops could have got easy access to the enemy's territory and take over from there. However, this did not go to the plan they had in mind. This was because the Germans had found out their plan so they could stop it from happening. How they found out in unclear but it could be for the following reasons. That a radio message between the front and British generals had been intercepted by The Germans.
British soldiers captured during the raiding parties had been interrogated and revealed the plans.
The actual plan conceived by the British commanders was that unopposed British advance through No Man's Land which at the time was very dangerous but they decided to take that risk. Soon they would reach the barbed wire where they would cut it so they can advance further. Behind the wire there was the German trench system. The German trenches destroyed and the soldiers killed or taken. In the air there would be an Artillery spotting aircraft to warn the British troops and commanders about German artillery that might be ahead of them. After the German trench system there was a village which had machine gun posts that the Germans would use as a last resort. The plan was to destroy the village and its defences.