These positions took in the villages and small woods of the region, all of which, fortified during the previous two years, bristled with defence-works and machine-guns. Some of these villages (Courcelette, Martinpuich, Longueval, Guillemont and Combles), hidden away in hollows, were particularly deadly for the Allies; the defenders, unseen, were able to snipe the assailants as they appeared on the hill tops. The Allies had to encircle these centres of resistance before they were able to enter them. _South of the Somme._--The battle zone, bounded by the large circular bend of the Somme at Péronne, formed a kind of arena. The vast, flat table-lands of the Santerre district, separated by small valleys, descend gently towards the large marshy valley of the Somme, in which the canal runs parallel with the river. Owing to the narrowness of this zone, the Germans were forced to establish their positions close behind one another, and the latter were therefore in danger of being carried in a single rush. On the other hand, the assailants' rapid advance was first hampered, then held by the marshy valley, which prevented them from following up their brilliant initial success. During the battle, the Germans, driven from their first positions, hastily prepared new ones, and clung desperately to the counter-slopes of the hills which descend to the valleys. The Different Stages of the Offensive The offensive of the Somme, the general direction of which was towards Cambrai, aimed at reaching the main northern line of communications, by opening a gap between Bapaume and Péronne. The main sector of attack--between the Ancre and the Somme--was flanked on either side by diversion sectors north of the Ancre and south of the Somme. [Illustration: ATTEMPTED BREAK-THROUGH. _A breach was made south of the Somme, but the marshes prevented development, while to the north, the offensive was held on the Ancre lines._] Putting to profit the German failure at Verdun, where the enemy masses, after appalling sacrifice of human life, gradually became blocked in a narrow sector (7½ miles in width), the Allies widened their front of attack. After an effective "pounding" by the guns which annihilated all obstacles to a considerable depth, the assaulting waves went forward simultaneously along a 24-mile front, feeling for a weak sector where a breach could be made. The attack was a complete success in the diversion sector, south of the Somme, thanks to the nature of the ground, but, as previously stated, it was not possible to follow it up immediately. North of the Somme the British offensive was held. Warned by the immense preparations, the Germans were not taken unawares. Their reserves flowed in and resisted on new defensive positions. The advance of the French 6th Army was slowed down to correspond with that of the British. The Battle of Attrition _(See the sketch-maps on pages 13, 18, 27.)_