My first Corps conference dealing with the forthcoming operations was held at my Headquarters at Assevillers, on September 23rd. The American Generals Read, Lewis and O'Ryan, with their respective Staffs, attended, as also did the Australian Generals Maclagan, Brand and Mackay, who were members of the Australian Mission to the American Corps. None of the Australian Commanders destined to take part in the operations attended on this day, for two reasons, firstly, because I intended to confine myself entirely to that portion of the operation which concerned the American troops only, and secondly, because the date of the battle had not then been decided, and I wished to run no risk of confusing executive action by any premature announcements to the Australians, which subsequent events might modify.
The American rôle, had, however, sufficiently crystallized to enable me to explain it to the assembled Generals in great detail. As will subsequently appear, it was a plan which had, intentionally, been reduced to the simplest possible elements. It was to be a straightforward trench to trench attack, from a perfectly straight "jumping off" line to a perfectly straight objective line, under a dense Artillery and Machine-Gun barrage, and with the assistance of a large contingent of Tanks.
The advance was to be at a deliberate pace, and if due regard were had to a few elementary precautions, should prove a simple task for the American Infantry. It was, indeed, on quite stereotyped lines, such as had so often carried the Australian Infantry to victory in set-piece battles such as Messines, Broodseinde, Hamel and the first phase of August 8th.
It was, however, borne in upon me, very soon after this Conference opened, that I was now confronted with quite a different proposition from that to which I had been accustomed in the conferences attended by my own Divisional Generals. The exposition of the plan itself was brief and simple, but it elicited such a rain of questions, that in the end I found myself compelled to embark upon a very detailed exposition of the fundamental principles of my battle practice.
With blackboard and chalk, maps and diagrams, I had to speak for more than three hours in an endeavour to explain methods and reasons, mistakes and remedies, dangers and precautions, procedures and expedients. The proceedings left me with no doubt that the American Generals became fully informed as to the tasks and duties allotted to them, and fully understood them.
In the light of after events, I am not so sure that they succeeded in passing on the information to their subordinates—not by reason of any shortcomings on their own part, for they impressed me as able, strong men—but because their Divisions had not yet learned the methods and machinery of effectively and rapidly conveying instructions to large bodies of troops.
In one particular, subordinate though vital, there certainly was a serious failure to reach the troops. The enemy had, during 1916, met our assault tactics with an answer which proved disastrously effective against us until we had learned how to meet it. He provided his trench systems with many and roomy shell-proof dug-outs. Whenever our barrage fell upon his trenches, his garrisons promptly took cover in these dug-outs. When our assaulting infantry reached the enemy trenches they found but few of the enemy there, and they rushed headlong forward to the next objective trenches. From out of their dug-outs streamed the enemy, faced about, attacked our assaulting lines in rear and withered them with fire. Many an attack by the British on the Somme failed for just such reasons.
In 1917 we evolved, and applied for the first time at the battle of Messines, an effective answer to such tactics. Close on the heels of our first line of assaulting troops came a second line, whose rôle was to occupy the captured trench immediately, and to "mop it up." This meant the killing or disarming of all enemy found in hiding, the picketing of the entrances and exits of all dug-outs, and laying siege to them until their occupants surrendered, a course to which they were encouraged by a liberal use of phosphorus bombs or Mills's grenades.
This process of "mopping up" became an integral part of our attack procedure. Australian infantry soon learned its importance, and practised the method with a thoroughness and efficiency to which I remember no exception. Even a junior sergeant commanding a dozen men could be relied on to take all measures necessary to ensure that no enemy was ever left in hiding and unguarded behind his little party as they advanced.