On Saturday, 1st July 1916 when the Battle of the Somme began the 3rd Brigade was at Les Brebis north west of Lens and it was not until Tuesday, 11th July 1916 that they arrived at Albert to enter the battle.
The 3rd Brigade, 1st Division began relieving the 7th Division on the night of Friday, 14th July 1916 when 1 SWB took over the positions of the Cameron Highlanders in Lozenge Wood. At 05:30 hrs the following morning 2 WELCH moved forward to Fricourt and then up to Bazentin le Petit Wood to support 1st Battalion, the Loyal North Lancashire Regiment [1 L N LANCS] of the 2nd Brigade in an attack on 1,200 yards of the German frontline northeast of the wood. The attack went in at 09:00 hrs and by 09:50 hrs 250 yards of the enemy's front and support trenches had been gained. Enemy machine gun fire and the battered state of the captured trenches held up any further advance. At 16:30 hrs 1 L N LANCS closely supported by 2 WELCH made another attempt to push forward, but this was thwarted by heavy machine gun fire.
At 21:30 hrs 2 WELCH took over the front from 1 L N LANCS who moved back to Mametz Wood. At 22:00 hrs 2 WELCH attacked again and managed to take a further 400 yards of enemy trench during the night including two important trench junctions. 1 SWB moved forward to support 2 WELCH in place of 1 L N LANCS.
Sunday, 16th July 1916 was spent consolidating the gained positions.
The 3rd Brigade was ordered to make a further attack against the German Second Line at midnight that night and the 2nd Battalion, the Royal Munster Fusiliers [2 R MUN FUS] moved up on the left and the 1st Battalion, the Gloucestershire Regiment [1 GLOUC] moved up on the right in preparation for the attack. The artillery spent the day cutting the wire and following a ten minute hurricane bombardment the attack went in on schedule with 2 WELCH bombing in from the right in cooperation with the attack and 1 SWB remaining in support. When the attack went in at midnight the 1st Battalion, the Northamptonshire Regiment [1 NORTH'N] moved forward to occupy the trenches vacated by 2 R MUN FUS and 1 GLOUC. The attack managed to reach 300 yards beyond their objective, but being too exposed they retired to the captured German Second Line at dawn. Strong points were established some distance up the communications trenches, which were renamed Welsh Alley and Gloster Alley, and 1 SWB formed a defensive flank on the left in Black Watch Alley. Later on Monday, 17th July 1916 patrols were sent forward to reconnoitre the German Switch Line, which was now the next enemy position to the front.
In the evening of the 17th the 2 R MUN FUS was ordered to extend their line to the left facing the Pozières to La Sars road in conjunction with a preliminary attack by the 34th Division against Pozières. However, the 34th Division's attack did not materialize and the 2 R MUN FUS operation was postponed.
Throughout Tuesday, 18th July 1916 consolidation of the gains made on the night of 16th/17th continued and patrols were sent forward. That evening the 2nd Brigade moved forward and relieved the 3rd Brigade which then moved back to trenches between Becourt and Contalmaison. On Wednesday, 19th July 1916 they exchanged places with the 1st Brigade moving back to Becourt Wood. On Thursday, 20th July 1916 the 3rd Brigade moved back to Albert where the Welsh battalions occupied positions in the southeast of the town for the next two days.
In the afternoon of Saturday, 22nd July 1916 the 3rd Brigade moved back towards the front and took over positions between Scotts Redoubt and Becourt Wood. That night the 1st and 2nd Brigades attacked the German Switch Line.
At 10:00 hrs on Sunday, 23rd July 1916 orders were received by the 3rd Brigade to move back to Albert. They were to leave two battalions in the vicinity of Becourt Wood and these were 1 SWB and 1 GLOUC. 2 WELCH and 2 MUN FUS were to move back to Albert. However, new orders were received at 19:30 hrs for the 3rd Brigade to relieve the 2nd Brigade. The first two battalions being relieved by 07:00 hrs on the 24th and the remaining two battalions by 10:00 hrs that same day. The 3rd Brigade deployed with 1 SWB on the left and 1 GLOUC on the right in the frontline trenches, 2 WELCH in front of Contalmaison and 2 MUN FUS at Scotts Redoubt.
Brigadier-General Davies took over responsibility for the line at 12:30 hrs and held a conference with CO 1 SWB and CO 1 GLOUC. At that conference he told Lieutenant Colonel Bertram William Collier, CO 1 SWB, that his battalion was to attack at 02:00 hrs on Tuesday, 25th July 1916 in conjunction with the 3rd Australian Brigade on their left in Pozières with 1 GLOUC in support in Munster Alley. When the attack by 1 SWB went in it was held up by heavy machine gun fire and failed to achieve its objective.
1 SWB was withdrawn to Peake Wood at 10:30 hrs on the 25th and 1 GLOUC took over the line. This left them somewhat extended and it was decided to send 2 WELCH to relieve them. At 16:30 hrs 2 WELCH started forward to relieve 1 GLOUC in the frontline east of Pozières. At the same time 2 R MUN FUS moved forward from Scotts Redoubt to take over the vacated positions of 2 WELCH. On relief 1 GLOUC moved into the positions vacated by 2 R MUN FUS at Scotts Redoubt.
On the night of the 25th 2 WELCH was required to attack up Munster Alley and to seize 250 yards of the trench from its junction with OG1 and the new German trench running into it from the north. At the same time a new trench was to be dug from the junction with the new German trench to Lancs Trench and two officers and 50 other ranks from 1/6th WELCH were sent forward to assist with this latter task. This attack was timed to take place at 01:00 hrs on Wednesday, 26th July 1916. At 01.00 hrs the attack was postponed as the reliefs were still in progress and it was all confusion with battalions moving from one location to another. When the attack finally went in at 03:00 hrs it failed to achieve any success.
During the morning of the 26th it was reported that 2 WELCH was in possession of point 41 and consequently they were ordered to bomb up Munster Alley from that point. The bombing attack was carried out by means of a communication trench that had been recently dug by 2 WELCH from OG1 to OG 2 between points 38 and 78, then along OG2 and up Munster Alley by the communication trench leading to point 41. 2 WELCH was initially successful seizing about 250 yards of the trench and reaching their objective. However, enemy reinforcements quickly counterattacked and forced them back. Whilst this attack was in progress the 69th Brigade began relieving the battalions of the 3rd Brigade. 2 WELCH was the last battalion to be relieved and this was complete by 02:00 hrs on Thursday, 27th July 1916. On relief the 3rd Brigade marched to Millencourt.