Now let us look closely at the portion of the German line which was to be assaulted. From the village of Auberive (page 336) the trenches ran eastward. Beyond Souain a series of hills lay in front of the French line, and on each of them a redoubt had been erected. The Germans had held this position since the Battle of the Marne, and for more than a year they had striven to make it impregnable. In many cases the trenches had walls of concrete, and the wire entanglements were as much as sixty yards deep. In front of the entanglements the ground had been honeycombed with mines, and strewn with sharpened stakes and obstacles of all kinds. Every German fired from behind a shield of armour plate, and at every fifteen yards along the trenches there was a machine gun. Here and there were revolving steel turrets, each containing a quick-firing gun. In some places there were five lines of trenches, one behind the other, all linked together so as to form a labyrinth very similar to that which the French had captured in Artois. Remember that these trenches only formed the first line of German defence. Behind them was a second line, and between the two were the artillery. Light railways came right down to the front, so that troops and ammunition and supplies could be moved very readily and speedily. The Germans boasted that they had created an inland Gibraltar, and they smiled superior when their aviators told them what preparations were going on behind the French lines. They were quite certain that nothing could shift them. [Illustration: The Great French Advance in Champagne. _By permission of The Graphic._ While the British advanced between La Bassée and Lens, the French assaulted the German lines on a seventeen-mile front in Champagne. They carried all before them, and captured 21,000 prisoners and over 120 guns. A British surgeon who witnessed the onslaught tells us how the French dashed forward like an avalanche. "They are superb, these Frenchmen."] Of course it would never do for the French to attack in Champagne while the rest of the Allied troops lay quiet in their trenches. The enemy must be engaged at various points all along the line, so that he could not mass reinforcements against the great attack. Further, he must not be allowed to know exactly where the main thrust was to take place. The Allies intended, as we shall learn later, to make a big offensive between La Bassée and Lens, and to fight holding battles elsewhere. Early in the month of September, during perfect autumn weather, a general bombardment began along the whole front. The airmen were very busy, and in the third week of the month there were no fewer than twenty-seven fights over the British front alone. On 23rd September the bombardment began to grow very violent. The guns had begun the overture to the great drama on which the curtain was now about to rise. * * * * *