The VIth, IVth, and Vth Corps of the Third Army were to attack on the line Beaucourt-sur-Ancre—Moyenneville, a frontage of 17,000 yards, with the object of driving the enemy eastwards across the Arras-Bapaume road and of forcing him from the Somme area. Tanks were only to operate between Moyenneville and Bucquoy, as the ground south of this frontage was unsuited to tank movement; for this reason no tanks were allotted to the Vth Corps.
The allotment of tanks was as follows:
| VIth Corps | 2nd and 3rd Tank Brigades. |
| IVth Corps | 1st Tank Brigade. |
Owing to the little time available and the necessity for maintaining secrecy it was not possible to carry out any training with the divisions of the Third Army; many of these, however, had previously attended demonstrations at Bermicourt, to supplement which notes were now issued and as many lectures as possible given prior to this attack.
Another difficulty was reconnaissance, time for which was most limited. Again previous work came to the rescue; for many officers in the Tank Corps had carefully studied the area of attack prior to the Second Battle of the Somme and had fought over it during the German spring offensive.
On the Fourth Army front the IIIrd Corps, on the left of this Army and north of the river Somme, was to attack between Bray and Albert. The 4th Tank Brigade was to assist in the attack and its machines were allotted to divisions as follows:
| 4th Battalion | 10 tanks to 12th Division. |
| „ „ | 4 tanks to 18th Division. |
| 5th Battalion | 10 tanks to 47th Division. |
| 1st Battalion | 15 tanks to Fourth Army reserve. |
South of the Somme the 5th Tank Brigade was ordered to co-operate with the Australian Corps on the front Herleville—Chuignolles; the object of the attack being to capture these villages and the rise running east of them. Tanks were allotted as follows:
| 8th Battalion | 12 tanks to 32nd Division. |
| 2nd Battalion | 12 tanks to 1st Australian Brigade. |
| 13th Battalion | 12 tanks to 2nd Australian Brigade. |
The battle of Bapaume, which began on August 21, is of particular interest in that it was the first attack launched against a new tactical system of defence recently adopted by the enemy, namely, the holding of his reserves well in rear of a lightly held outpost line. In conformity with the principles of this system of defence in depth the Germans had withdrawn their guns behind the Albert-Arras railway; this eventually complicated the tank attack, for had they remained forward, as so frequently they had heretofore done, they would have been surprised and captured during the first phase of the battle; as it was, they accounted for many of our machines during the third phase.