Behind the “forward zone,” at a distance of from half a mile to three miles or more, came the “battle zone,” arranged on the same plan, except that it had no outposts. It was a defence in depth, elaborately wired, and studded with strong-points. A mile or two in its rear lay the third and final defensive zone, which in March was little more than a sketch. The theory of the system was that the “forward zone” would break up the cohesion of any assault, and that the “battle zone” would be impregnable against an attack thus weakened. Consequently the alternative positions in the rear—the third zone and the Péronne bridgehead—were not serious defences. Considering the small number of men available, it was not possible to provide any further safeguards in the time. On the “battle zone” rested the hope of resistance for the Third and Fifth Armies. If it failed to stand, the situation would be grave indeed, for there were no prepared defences to fall back upon, and no immediate hope of reserves. The 9th Division formed the extreme left of the Fifth Army, with, on its right, the 21st Division under Major-General David Campbell; and on its left the 47th (London Territorial) Division under Major-General Sir G. F. Gorringe—the right flank of Byng’s Third Army. The 9th held its front with two brigades, the 26th on the left and the South Africans on the right, with the 27th in reserve. The South African sector covered some 2,000 yards from just north of Quentin Redoubt to just south of Gauche Wood. The Brigade was distributed in depth—that is to say, it was responsible not only for the front line, but for all other trench lines to the depth of about a mile. This made it impossible for it to man the entire length of its trenches, so its front was held by a series of posts placed at key positions, and so arranged as to enable their occupants to cover the whole ground with their fire. As the hour of attack approached, the “forward zone” was held by the 2nd Regiment on the right and the 1st on the left, with the 4th Regiment in reserve in the “battle zone.”