On the first day of the Battle of the Somme, 1st July 1916, the 9th Devons, followed by the 8th Devons, were given the task of attacking German trenches below the fortified village of Mametz and in the direction of Fricourt. These Devonshire Battalions were part of the 7th Division. Other battalions of that Division would be attacking alongside the Devons.

This sector of the British front line was one of the few places where the German lines were overlooked. The British trenches ran along the top of a small hill and then down to Mansel Copse before going off at the end of the copse to slope down the hill at an angle and cross a main road. The front line trench occupied by the Devons ran behind Mansel Copse which was located on a long bank of chalk. The ground on the enemy side of the copse sloped down the road connecting Albert to Peronne. The Devons' front line trench had been battered by German shelling before the attack so their start line was an assembly trench about 250 yards up the hill.

Before the attack, one of the Company Commanding Officers, Captain D. L. Martin, had forecast that a machine gun, placed in the Mametz village cemetery by the enemy, could cause heavy casualties. Unfortunately, there was a machine gun in that very spot (called "The Shrine") and it had survived the heavy bombardment which had preceded the attack. As the 9th Devons came past Mansel Copse into the valley along which they had to make their attack, they were caught by the machine gun fire, as were a battalion of the Gordon Highlanders who were attacking alongside them. Although the 9th Devons got into the German trenches, they suffered such casualties as to exhaust their attack. The Gordons also suffered heavily. The 8th Devons were able to follow through and consolidate their gains.

After the attack a  burial party of the Devons, led by the Padre, gathered their dead and buried them in their original front line trench behind Mansel Copse at an evening service held on the 4th of July. This trench burial site became "The Devonshire Cemetery" which contains 163 graves. The 9th Devons lost 123 men while the 8th Devons lost 38 of their men. The remains of two Royal Artillery men were added at a later date. The burials include the remains of 10 unknown soldiers, all of them from the 9th Devons.