"'Heartiest congratulations to you all on fine work on 16th and 17th May 1917, and especially on General Burn and 152nd Infantry Brigade, whose tenacity and pluck saved an awkward situation. The Division may well be proud of their latest achievement.'" General Allenby, commanding the Third Army, wired: "Convey to 51st Highland Division my congratulations on their great gallantry at Roeux and the chemical works." On the night 16-17th May the 153rd Brigade and the 5th Gordon Highlanders were relieved in the line, the 6th Black Watch taking over the left sub-sector, and the 4th Seaforth Highlanders the right. On the extreme north of the Divisional boundary about fifty men of the 6th Seaforth Highlanders could not be found in the darkness, and were in consequence not relieved until the following night. The command of the front was then divided between the 153rd and 154th Brigades; the 152nd Brigade moved back to Arras to recuperate and refit. They were not employed again in this sector, the other two brigades remaining permanently in the line until the Division was relieved on 31st May. From the day following the battle until the date of relief the 153rd and 154th Brigades were severely and constantly bombarded by guns of all calibres up to 8-inch. The enemy was extremely active in the air, and made considerable use of aeroplanes in co-operation with artillery. The Divisional war diary for 24th May runs as follows: "Hostile shelling intermittent but accurate. Enemy aeroplanes for the past week have had an uninterrupted survey of our lines. Between 3 P.M. and 3.30 P.M. an aeroplane registered the right brigade headquarters, scoring several direct hits, and causing considerable casualties." The following day the right brigade was shelled out of its headquarters, and had to move back to an embankment west of Athies. The activities of these aeroplanes were to a certain extent checked by employing Stokes guns to engage them with air-bursts. It was the first time that the use of Stokes guns as anti-aircraft guns was attempted; and though it was almost impossible to obtain any degree of accuracy, the Stokes bombs certainly had a deterring effect on the enemy's pilots. In spite of the continual bombardments, with the assistance of the 8th Royal Scots, the field companies, and some tunnellers, the troops in the line made rapid progress in the consolidation of the position. The trenches everywhere were deepened, wire entanglements erected, and the construction of dug-outs begun.