In France, the regiment regained battalion strength in preparation for the Battle of the Somme. The regiment, still with the 29th British Division, went into the line in April 1916 at Beaumont-Hamel. Beaumont-Hamel was situated near the northern end of the 45 kilometre front being assaulted by the joint French and British force. The attack, originally scheduled for 29 June 1916 was postponed by two days to July 1, 1916, partly on account of inclement weather, partly to allow more time for the artillery preparation. The 29th British Division, with its three infantry brigades faced defences manned by experienced troops of the 119th (Reserve) Infantry Regiment of the 26th (Wurttemberg) Reserve Division. The 119th (Reserve) Infantry Regiment had been involved in the invasion of France in August 1914 and had been manning the Beaumont-Hamel section of the line for nearly 20 months prior to the battle. The German troops spending a great deal of their time not only training but fortifying their position, including the construction of numerous deep dugouts and at least two tunnels.
The infantry assault by the 29th British Division on 1 July 1916 was preceded ten minutes earlier by a mine explosion under the heavily fortified Hawthorn Ridge Redoubt. The explosion of the 18,000 kilogram (40,000 lb) Hawthorn Mine underneath the German lines successfully destroyed a major enemy strong point but also served to alert the German forces to the imminent attack. Following the explosion, troops of the 119th (Reserve) Infantry Regiment immediately deployed from their dugouts into the firing line, even preventing the British from taking control of the resulting crater as they had planned. When the assault finally began, the troops from the 86th and 87th Brigade of the 29th British Division were quickly stopped. With the exception of the 1st Battalion of the Royal Inniskilling Fusiliers on the right flank, the initial assault foundered in No Man's Land at, or short of, the German barbed wire. At divisional headquarters, Major-General Beauvoir De Lisle and his staff were trying to unravel the numerous and confusing messages coming back from observation posts, contact aircraft and the two leading brigades. There were indications that some troops had broken into and gone beyond the German first line. In an effort to exploit the perceived break in the German line he ordered the 88th Brigade, which was in reserve, to send forward two battalions to support attack.
At 8:45 a.m. the Newfoundland Regiment and 1st Battalion of the Essex Regiment received orders to move forward. The Newfoundland Regiment was situated at St. John's Road, a support trench 250 yards (230 m) behind the British forward line and out of sight of the enemy. Movement forward through the communication trenches was not possible because they were congested with dead and wounded men and under shell fire. Lieutenant Colonel Arthur Lovell Hadow, the battalion commander, decided to move immediately into attack formation and advance across the surface, which involved first navigating through the British barbed wire defences. As they breasted the skyline behind the British first line, they were effectively the only troops moving on the battlefield and clearly visible to the German defenders. Subjected to the full force of the 119th (Reserve) Infantry Regiment, most of the Newfoundland Regiment who had started forward were dead, dying or wounded within 15 to 20 minutes of leaving St. John's Road trench. Most reached no further than the Danger Tree, a skeleton of a tree that lay in No Man's Land that was being utilized as a landmark. So far as can be ascertained, 22 officers and 758 other ranks were directly involved in the advance. Of these, all the officers and slightly under 658 other ranks became casualties. Of the 780 men who went forward only about 110 survived unscathed, of whom only 68 were available for roll call the following day. For all intents and purposes the Newfoundland Regiment had been wiped out, the unit as a whole having suffered a casualty rate of approximately 90 percent. The only unit to suffer greater casualties during the attack was the 10th Battalion of the West Yorkshire Regiment, attacking west of Fricourt village.
Although significantly understrength, the Newfoundland Regiment continued to see service and after taking on reinforcements was back in the front line on 14 July near Auchonvillers. On 17 July the 88th Brigade was transferred to a quieter portion of the Western Front. In the weeks and months following the attack, the surviving officers wrote letters of condolence to families and relatives in Newfoundland. A period of recovery coupled with additional reinforcements would eventually help the regiment return to full strength. Six weeks later they were beating off a German gas attack in Flanders. Subsequently they distinguished themselves in a number of battles; back on the Somme at Gueudecourt in October 1916; on 23 April 1917, at Monchy-le-Preux during the Battle of Arras, where they lost 485 men in a day but checked a German attack. In Flanders during the Third Battle of Ypres the battalion attacked on 16 August at the Battle of Langemarck and on 9 October 1917 the battalion formed the left flank of 29th Division's attack as part of the Battle of Poelcappelle. In November 1917 at MasniÃ¨res-Marcoing during the Battle of Cambrai the regiment stood its ground although outflanked and in April 1918 stemmed a German advance at Bailleul. Following a period out of the line, providing the guard force for General Headquarters at Montreuil, they joined the 28th Brigade of the 9th (Scottish) Division and were in action again at Ledegem and beyond in the advances of the Hundred Days Offensive during which Thomas Ricketts became the youngest soldier of the war to win the Victoria Cross.