After the enemy positions in this sector had been captured by the Division in April 1917, an examination was made of the German crater posts. It was astonishing to see to what an extent he could look down into the British trenches. It was realised at the time that men walking along the trenches were often under observation, and, indeed, the casualties from sniping proved that this was so. It was not, however, appreciated till later to what a degree men in the trenches, particularly the communication trenches, were visible to the Germans. In some places even the duck-boards at the bottom of the trenches were in enemy view.
The result of this situation was that at first the enemy made a considerable bag by sniping; Colonel Campbell, commanding the 4th Seaforth Highlanders, was killed by a sniper the day after the Division had taken over the line. Within a fortnight his successor was killed in a similar way.
However, the Highland Division, with a number of stalkers and gillies in its ranks, had probably the best material the country produced from which to make snipers. After a short period devoted to organisation and training, the snipers of the Division soon obtained a superiority over the enemy. It, however, always remained a sector in which the greatest care had to be exercised in looking over the parapet or in moving amongst the saps and forward boyaux. Enemy snipers were continually shattering periscopes with rifle shots.
In the Labyrinth the Division made its first organised raids. These raids consisted in heavily barraging a certain area, then at a given moment the barrage lifted off certain portions of this area and allowed the assaulting infantry to enter it. The barrage remained down on three sides of the area to protect the attackers who entered it from the fourth side from interference from without while they were destroying the Germans within. This form of barrage, originally first employed by the Germans, was known as the Box Barrage.
The two most successful raids which took place during this period were those carried out by Lieutenant E. A. Mackintosh of the 5th Seaforth Highlanders (since killed in action), and Captain Herd of the 6th Black Watch. The former was in consequence awarded the Military Cross, and the latter the D.S.O.
Raids subsequently became of such frequent occurrence that want of space forbids description of them all. Certain raids have, however, been selected for description, which will be dealt with later.
These raids in particular brought to light certain facts concerning German trench construction. The German trenches did not resemble the small ditch-like trenches commonly seen at schools of instruction and training grounds. They can better be compared to the marker’s gallery in a rifle range. They were ten to eleven feet deep, with the sides for the most part revetted with planks. To get into them was not easy; to get out of them still less easy; while evacuating the wounded from them was a matter of very considerable difficulty. In fact, in the case of Mackintosh’s raid, it is doubtful if his wounded could have been brought back to our lines at all had not a sally-port through which the more severely wounded were carried been discovered.
On 21st May the enemy became extremely active. The Divisional artillery were heavily bombarded during the afternoon and evening with lachrymatory shells, as also were the communication trenches. At the same time the trenches of the 25th Division on the left of the Highland Division, and of the 47th Division, were intensely bombarded. Marœuil, Anzin, and Mont St Eloi were also shelled during the night, as well as several villages in rear of the 25th and 47th Divisional areas. At Marœuil an 8-inch shell burst in the 152nd Brigade headquarter office within a few seconds of the clerks having left it for the cellar, completely wrecking it, and killing the staff captain’s two horses, which were tethered outside it.
This bombardment culminated in a successful hostile attack, the enemy, with apparently little difficulty, attaining his object and establishing himself firmly on the western slopes of the Vimy Ridge.
The cause of his success was due to the fact that he succeeded in secretly concentrating a large force of artillery with which to support his attack. He then subjected all the trenches involved to a bombardment of an intensity which in those days was considered unparalleled. The garrisons of the trenches attacked were almost completely without the protection of shell-proof dug-outs, and the defenders were thus for the most part killed or wounded by the bombardment before the infantry attack was launched.