In February 1917, the British Army issued "Manual SS 143" on the subject. The British made the platoon the basic tactical unit rather than the company as in 1916. The platoon was made up of four sections, Lewis Gun, rifle grenade, grenade and rifle. The new organisation allowed the platoon to make best use of the trench-fighting equipment that had arrived in adequate quantities since the beginning of the Battle of the Somme. They were also supported by sophisticated artillery flash spotting and sound-ranging, something the German Army never perfected, instead relying on the aural method with ever more accurate measuring devices.