Finally the air photos became spotted with curious small rectangular mounds, which from their appearance on the photos came to be known as “lice.” The idea of trying the effect of a direct hit on one of these “lice” with a 4·5 howitzer occurred to General Oldfield, and a shoot was in consequence arranged. The result was conclusive; every time a “louse” was hit it exploded. They were, in fact, dumps of ammunition scattered broadcast about the valley of the river Agache. The 256th Brigade, R.F.A., caused over a hundred of these explosions within an hour and a half.
It was then decided to test the gun emplacements, and see whether ammunition had been stored in them. The result showed that every gun position, whether it was occupied by a gun or not, contained ammunition.
These signs were unmistakable.
Prisoners captured on various parts of the front also reported that the Germans were building tanks in large numbers. Two measures of anti-tank defence were therefore taken. Fields of anti-tank mines were laid, covering all the main avenues of approach, such as valleys and roads. The mines used were the old 60-pounder trench-mortar bomb, fitted with a special fuze, which were sunk just level with the surface of the earth. In laying one of these mines, a most unfortunate accident occurred. A bomb from some unknown cause exploded, killing and wounding one officer and eighteen men of the 152nd Trench-Mortar Battery.
Seven 18-pounders and three 15-pounders were also employed as anti-tank guns, being placed in positions about the support and reserve line from which they could cover the main avenues of approach over open sights.
By the middle of March the trench system consisted of the following: The front system, composed of the front, support, and reserve lines, the two former being continuous trenches held by section and double-section posts, the third a series of defended localities and portions of trenches, all heavily wired. The intermediate line, running from the north of Hermies, north of Doignies, north of Louverval, through Louverval Wood to the Divisional boundary.
The Corps line—i.e., the Hermies-Beaumetz-Morchies line.
Behind this trench system the Army (Green) line traversed the Divisional sector. It consisted of an old German trench, heavily wired, running from Ypres to Beugny, and thence northwards.
By this time the brigades had all been reduced from four to three battalions, the 9th Royal Scots, the 5th Gordon Highlanders, and the 8th Argyll and Sutherland Highlanders having been transferred to the 62nd Brigade. The departure of these units was a great blow both to the Division and to the battalions, but it was due to a definite change in organisation throughout the Expeditionary Force in France, to which no exceptions could be made. With only nine infantry battalions available, all three brigades were in the line—154th Brigade on the right, 152nd in the centre, and the 153rd on the left. Each brigade had two battalions holding the trenches in depth from the front line to the Corps line inclusive.
The order of battle ran from right to left, 4th Gordon Highlanders, 7th Argyll and Sutherland Highlanders, 6th Gordon Highlanders, 5th Seaforth Highlanders, 7th Black Watch, 6th Black Watch, the battalions in brigade reserve being the 4th and 6th Seaforth Highlanders in Lebucquière, and the 7th Gordon Highlanders at Beugny, all ready to man the Beaumetz-Morchies line (Corps line) if required.