December 1915 was a particularly hot time in the Hohenzollern Redoubt with mine warfare. 14 men died when a platoon of A Company was buried on Christmas Eve. In January 1916, the London Irish were back in the centre of Loos. Trench strength of the battalion was down to 16 officers and 381 men again as the year began. The London Irish moved to Raimbert in mid February, where the Battalion Concert Party was formed, and was named the ‘Emeralds.

In the spring of 1916, the 1st Battalion moved forward to the Souchez area to take over from the French. The London Irish line was in the Carency sector on the extreme left of Vimy Ridge. This sector remained relatively quiet at first although enemy shell fire was troublesome. During April, while in reserve, the London Irish suffered an epidemic of measles starting with D Company and all of these men had to be isolated. Fifteen men were killed by shell fire during the first four months of 1916.

In May 1916, the Germans made several furious attacks on the front line held by the London Irish. On 10th/11th May, the battalion had to defend against a strong enemy bombing attack followed by artillery fire that did much damage to our forward and support trenches. Later in the same month, in taking over in the trenches at Vimy Ridge again, it was necessary for A Company led by Captain Hobbs to put in a counter attack in the Zouave Valley in support of the 8th London Regiment (Post Office Rifles). However, with too few troops being employed, the attack was not successful, Captain Hobbs being wounded and 2/Lieuts Butcher and Conlan and about twenty other ranks killed. On the 23rd May, Brigadier General Thwaites was wounded and when Colonel Tredinnick took over 14 Brigade, Major JR Trinder became CO of the London Irish. In all there were 33 fatalities during May.

After the May actions, the battalion remained in Corps reserve until 11th June 1916, when they entered the line once again, taking over trenches between Bully Grenay and Souchez. A great deal of effort was spent in making the trench system serviceable although this was severely hampered by the aggressive behaviour of the enemy. The middle of July was spent at Albain St Nazaire and the Lorette Heights, where conditions were quieter and sleep was possible. The London Irish left for Corps reserve on 27th July and stayed there until 4th August when they were ordered to march south to Gavennes. Here, intensive training in wood fighting was practised, some of it in Crecy woods where one of the London Irish remembered that the Black Prince had won a glorious victory for England exactly 570 years before. There were rumours of a new secret weapon that could cross trenches, go through barb wire and tackle machine guns. High hopes were entertained of this wonder, introduced as the tank. By the end of August, all ranks were conscious of the fact that they would within a few days be engaged in the Somme battles and perhaps see this new weapon on action.

The 2nd Battalion had moved to France with the 60th Division on 23rd June 1916. On embarkation, the CO was Lt Colonel WH Murphy and the total numbers sailing were 34 officers and 938 other ranks.

Landing at Le Havre, the battalion moved to Neuvulle St Vaast and entered the line for a tour of instruction on 1st July 1916, the day that the great battle of the Somme began. This sector was at the foot of Vimy Ridge and the 2nd Battalion remained there in and out of the line until 24th October 1916, casualties being two officers and thirty other ranks killed through minewerfers and trench raids. Towards the end of August, the 2nd Battalion, as the left battalion of the 60th Division, fought side by side with the first battalion, the right battalion of the 47th Division, but there was little opportunity for meeting.