This, coupled with the readjustment of the northern boundary with the Third Corps, as already narrated, reduced the total frontage for which I remained responsible to about ten thousand yards, an extent which was never again exceeded. It was still, however, in my judgment, too long a frontage for an effective pursuit by only two Divisions, and arrangements were initiated on the same day to bring back the Third Division into line.
During September 5th I advanced my front to the line Athies—Le Mesnil—Doingt—Bussu. Severe fighting took place near Doingt. Opposition came mainly from machine guns; but isolated field-guns also gave us trouble. We captured that day about a hundred and fifty prisoners.
Next day my Third Division came into the line on the north. I divided my frontage equally between the three Divisions, placing each on a single Brigade front. This was, in fact, a repetition of the order of battle which had carried us so successfully and rapidly up to the Somme.
Each front line Brigade took up the rôle of Advanced Guard to its Division. The 11th Brigade led the Third Division; the 8th Brigade led the Fifth Division, while the 97th Brigade covered the 32nd Imperial Division.
For the first time in the war I found an opportunity of employing my Corps Cavalry (13th Australian Light Horse) on other than their habitual duty of carrying despatches, or providing mounted escorts to convoys of prisoners of war. Here at last was a chance for bold mounted tactics, as the county was mainly open and free of wire and trenches.
To each Division I therefore allotted a squadron of Light Horse for vanguard duty, together with detachments of the Australian Cyclist Battalion. These troops more than justified their employment by bold, forward reconnaissance, and energetic pressure upon the enemy rearguards.
So promising, indeed, was the prospect of the useful employment of cavalry, that I prevailed upon the Army Commander to endeavour to secure for my use a whole Cavalry Brigade. Brigadier-General Neil Haig (cousin of the Field Marshal) was actually sent for and placed under my orders. I duly arranged a plan of action with him, but before the 1st Cavalry Brigade, stationed many miles away, had completed its long march into my area, the situation had already changed, and the employment of Cavalry on the Fourth Army front had to be postponed until a much later date.
A juncture had arrived when it became imperative for me to consider the possibility of affording some relief to the three line Divisions; all of them had been fighting without respite since August 27th. The troops were so tired from want of sleep and physical strain that many of them could be seen by the roadside, fast asleep. These three Divisions had almost reached the limits of their endurance.
It was essential, however, that they should be called upon to yield up the last particle of effort of which they were capable. Every mile by which they could approach nearer to the Hindenburg defences meant a saving of effort on the part of the fresh waiting Divisions, whom I had earmarked for the first stage of our contemplated assault upon that formidable system; a system which I knew to be too deep to be overwhelmed in a single operation.
It was for this reason that I was compelled to disregard the evident signs of overstrain which were brought to my notice by the Divisional Generals and their Brigadiers, and which were patent to my own observation of the condition of the troops. I arranged, however, two measures of immediate relief, the first being to set a definite limit of time for the further demands to be made upon the line Divisions. This was fixed for September 10th. The second was to issue orders that the rate of our further advance was to be controlled by consideration for the well-being of our own troops, and not by the rate of the enemy's retreat. If, in consequence, any gap should eventuate, touch with the enemy was to be kept by the mounted troops and cyclists.