In the first phase of the battle of Flanders the new system of German defence was formidable. It was that "elastic system" by which Hindenburg hoped to relieve his men from the destructive fire of our artillery by holding his front line thinly in concrete blockhouses and organized shell-craters with enfilade positions for machine-gun fire, keeping his local reserves at quick striking distance for counter-attack. Our first waves of men flowed past and between these blockhouses in their struggle to attain their objectives, and were swept by cross-fire as they went forward, so that they were thinned out by the time they had reached the line of their advance. The succeeding waves were sometimes checked by German machine-gunners still holding out in undamaged shelters, and our troops in the new front line, weak and exhausted after hours of fighting, found themselves exposed to fierce counter-attacks in front while groups of the enemy were still behind them. For several weeks there were episodes of this kind, when our men had to give ground, though the line of advance seldom ebbed back to its starting line, and some progress was made however great the difficulties. Still the "pill-box" trouble was a serious menace, costly in life, and new methods of attack had to be devised during the progress of fighting when the area of the 2nd Army was extended on our left so that the 5th Army was relieved of some of its broad battle front. Our heavy howitzers concentrated on every blockhouse that could be located by aeroplane photographs or direct observation, with such storms of explosive that if they were not destroyed the garrisons of machine-gunners inside were killed or stupefied by concussion. Our method of attack in depth, as at Wytschaete and Messines--battalions advancing in close support of each other, so that the final objective was held by fresh troops to meet the inevitable counter-attacks--succeeded in a most striking way, in spite of the fearful condition of the ground. The enemy changed his new method of defence to meet this new method of attack. He went back to strongly held lines with support troops close forward, and had to pay the penalty by heavier losses under our artillery. The abominable weather and state of ground were his best lines of defence, and in August and October he had astounding luck.