At Loos, in January and February 1916, the division was introduced to trench warfare and suffered greatly in the Battle of Hulluch. Personnel raided German trenches all through May and June. In late July they were moved to the Somme Valley where they were intensively engaged in the Battle of the Somme. Lieutenant General Hubert Gough, the British Fifth Army commander, had asked, at the end of 1915, for the division to be placed under his command, and had established the first corps school for the training of young officers. The 16th Division played an important part in capturing the towns of Guillemont and Ginchy, although they suffered massive casualties. During these successful actions between 1 and 10 September casualties amounted to 224 officers and 4,090 men; despite these very heavy losses the division gained a reputation as first-class shock troops. Out of a total of 10,845 men, it had lost 3,491 on the Loos sector between January and the end of May 1916, including heavy casualties from bombardment and a gas attack at Hullach in April. Bloodletting of this order was fatal to the division's character, for it had to be made good by drafts from England.