Being relieved on the 14th by the 1st Royal Berks, the Battalion moved into support and reserve lines, but on the 18th were in the trenches west of Ecurie, moving to a tent camp on the Roclincourt-Maison-Blanche road on the 22nd. Another move, to Maroeil, was made on April 23, and on the 25th the 17th Royal Fusiliers were relieved in the trenches west of Bailleul. On April 29, at 4 a.m., "B" Company took part in an attack on Oppy by the 1st Royal Berks and the 1st King's Royal Rifle Corps, and then the Battalion moved back into reserve trenches. On May 1 a composite battalion was formed of two companies of the 23rd Royal Fusiliers and two companies of the 1st Royal Berks, and moved forward to a position in front of Oppy to deliver an attack on the Oppy-Fresnoy line. Attacking on March 3, Fresnoy trench was captured with between sixty and seventy prisoners and a machine gun. Heavy counter-attacks were made by the Germans during the day, and, in view of these and the retirement of the troops on the right, it became necessary to retire along Fresnoy trench. At 3.30 a.m., on the night of May 3-4, the Battalion was relieved by the 15th Warwicks, and moved back to disused enemy trenches in the Roclincourt area, the total casualties sustained being 7 officers and 122 other ranks. On May 5 Lieutenant-Colonel Vernon having proceeded on leave, Major E.A. Winter assumed command, and on May 24 Lt.-Colonel Vernon having to report to the War Office on promotion to Brigadier-General, Major Winter was promoted Lieutenant-Colonel, and appointed to the command of the Battalion. On the same day the Battalion moved into the line again, relieving first the 1st Royal West Kents, and then the 22nd Royal Fusiliers. June 1 saw the Battalion relieved by the 1st King's Royal Rifle Corps in the front line (Oppy-Arleux line), and moved back to Deutscher House and Thelus Wood, working parties for the front line being provided each night. On the 4th, the 22nd Royal Fusiliers came in as the relief, and the Battalion moved to St. Aubyn for rest. This did not last long, for on June 8-9 the Battalion relieved the 1st King's Royal Rifle Corps in immediate support, Oppy-Arleux line, the casualties sustained being one other rank killed and two wounded. Then, relieving the 22nd Royal Fusiliers, the Battalion went into the front line, being relieved in turn on the night of June 13-14 by the Royal West Kents, and proceeded to Bray. On June 20 the Battalion was taken by omnibus to Beuvry, and on the 21st relieved the 2/5th Manchester Regiment in the front line, Cambrin left sub-sector, the casualties being two other ranks killed and six wounded. A German raid on the Battalion right was repelled at 3.30 a.m. on the 27th, and the 22nd Royal Fusiliers came in as relief on the evening of that day, the Battalion proceeding to Noyelles for rest.