This delicate work of marking out of the Infantry Start Line on the ground was invariably entrusted to the Engineers attached to the Brigades co-operating in the attack. The marking was done by laying out and pegging down broad tapes of white linen, which could be recognized in the dim light of early dawn. The whole work, had, of course, to be done unobserved by the enemy, and it was always a dangerous task.
Only the fact that we were in possession of reliable large scale maps, recording every feature of the ground, made it possible for the Engineers, resourceful as they were, to do this delicate work with reasonable accuracy. The battered condition of the country was always a difficulty; for it was never easy to recognize, on the ground, reference points, such as a road intersection, or the corner of a field, or a crucifix or similar land mark, which might aid the surveyors in getting their bearings.
Map G
The Infantry Start Line had, naturally, to be located so that the ground upon which the tapes were to be pegged down was ground which was already within our possession, or accessible to us without coming dangerously near the enemy. It was a necessary consequence that portions of our always irregular front line of posts or trenches would lie beyond or on the enemy's side of the tape line.
It was always a rule of our practice, therefore, that any Infantry posted in advance of the taped line should be withdrawn, behind the tapes, an hour before the time of Zero. It was also customary to order that all assaulting troops should be spread, in their appropriate dispositions, along the tape line, also one hour before Zero.
The result of these arrangements was that for the last hour before the actual opening of the battle, all Infantry intended to take part in the assault was deployed along the tapes in a perfectly straight line, all along the battle front, while no troops previously in occupation of posts or trenches in advance of the tapes were left out in front, exposed to the risk of either being hit by our own Artillery, or mistaken, in the half light of dawn, for enemies by our own Infantry.
Complex and difficult as these arrangements may appear from this description, they worked out in actual practice with the utmost smoothness. The resulting simplification of the Artillery plans, in this as in similar previous battles, more than justified their adoption.
A liberal use was also made of direction boards, which marked the routes by which each separate body of assaulting Infantry should, during the last night, march from its place of assembly to the taped line or "jumping off" line, and also to mark the position which it was to take up upon that line. Each board had painted upon it the name of the unit to which it referred. Such preparatory measures, troublesome as they were, greatly reduced the risk of any confusion or mistake, and lessened the fatigue of the assaulting troops.