In order to obtain observation and jumping-off ground for the attack on the main Hindenburg system it was necessary to clear the enemy from the positions still held by him forward of this line.
Rawlinson then proposed to undertake an operation on a large scale with the object of capturing the outer defences of the Hindenburg line along the whole front of the Fourth Army.
The capture of these defences, which would afford observation over the greater part of the main Hindenburg line proper, was of course an essential preliminary to any operation against the latter.
A series of partial offensives were therefore undertaken on the succeeding days, on both wings of the army, but with little real result; neither corps could succeed in attaining the final objectives of the first day's attack or clear the enemy entirely from the advanced defences of the Hindenburg line.
In view of the fact that the First and Third British Armies were faced with strong positions in the Canal du Nord and the Scheldt canal, which it was advisable to carry prior to the general attack on the Hindenburg line behind the latter obstacle, it was decided that these two armies should open their operations a day earlier than the Fourth Army, so as to draw off the German reserves from the front of that army, which had to deliver the main attack and was faced with the most formidable defences.