West of the lines of the 4th British Array, and dominating the valley
of the Ancre, the powerfully fortified Thiepval Plateau still remained
un-captured. This very strong system of defences comprised the village,
Mouquet Farm, and the Zollern, Schwaben and Stuff Redoubts.
In July, the British had gained a footing in the Leipzig Redoubt, which
formed the first enemy positions south of the Plateau. In August,
Pozières had been carried by the Australians. On September 15, the
British captured Martinpuich and Courcelette, and progressed beyond the
plateau to the east.