Retreat from Messines

The chapter 'The Retreat from Messines" in New Zealand Artillery in the Field, 1914-18 provides quite a detailed account of attack and counter-attack and difficulties faced by the Artillery around Messines from mid-March 1918. At this particular point 100 years ago, the history relates:

Several S.O.S. calls were answered during the day and evening of the 16th [April], and again next morning, when the enemy placed a heavy barrage along the front. Waggon lines at Westoutre were also shelled by hostile guns during the morning, resulting in a loss of men and horses, and the evacuation of the positions.
Forward observing officers kept closely in touch with the situation during the day, and batteries placed protective fire on threatened points, and engaged a great deal of enemy movement. The enemy brought up more guns, and hostile fire increased in volume, battery areas being severely shelled. The 5th Battery suffered heavy casualties during the morning of April 18th, losing two officers and five other ranks killed and twelve other ranks wounded; the battery was forced to evacuate the position, and as the other batteries were also coming under fire, the brigade withdrew to fresh positions.
By April 19th the front covered by the Brigade had been taken over by French troops, but the artillery in support was not withdrawn, and the brigade remained in the line supporting the French infantry until the 23rd, when all batteries were withdrawn to their waggon lines. The brigade proceeded the following day to the Staple area, where it remained in billets for three days. During this period sixty-three reinforcements and seventy remounts reached the brigade, and the guns were sent to the Ordnance Workshops for much-needed overhaul.
The brigade suffered heavy casualties during this brief period of active fighting, which besides being a severe trial on the endurance of the personnel at the guns and at the waggon lines, must be regarded as a most severe and searching, and in all respects successful, test of the initiative of commanding officers and their subordinates and of the efficiency of the whole brigade.