In General Haig's plan Messines was but a preliminary stroke to a renewed battle of Flanders. It relieved Ypres from danger on the south. The next thing was to press back the Germans on the east of the town. Here they sat on a series of hills, each a little higher than the one on its west side, running back to the ridge at Passchendaele eight miles east of Ypres. Through these positions General Haig proposed to fight his way by means of the limited objective. In his way stood skilfully constructed lines of small concrete forts, which the soldiers called (pill-boxes,* large enough for 20 to 30 men armed with machine guns, and strong enough to resist the shells of light artillery. These works were devised by the Germans in lieu of the deep dugouts which could not be used in the soil of this part of Flanders.
In order to deliver the proposed blow on the Ypres front General Haig redistributed his armies. First he extended the front of the 3d Army so that it held all the ground be tween the limit of the 1st Army at Arras and the limit of the French near Saint Quentin. As this process went on the 5th Army, which was thus forced out of the southern trenches, was moved northward and placed in line just north of the 2d Army, which held the sector inunediately south of the point of the Ypres salient. As the 3d Army continued to extend southward the 4th Army also moved northward and took position on the coast in the Nieuport sector. Thus the battle line was arranged as follows: At Nieuport, on a front of four miles, the 4th Army; south of it, on a 20-mile front but protected in part by the inundated area, were the Belgians; next, on a front of five miles, was the French 1st Army with General Anthoine for commander, fresh from his successes at Moronvillers; then came the British 5th Army on a seven-mile front from Boesinghe to the sector of the 2d Army, which carried the line southward as far as the Lys at Armentieres.
Out of the troops in this area General Haig arranged two striking forces. His 5th Army with the help of the French on its left and of the 2d Army on its right was to drive the Germans off the hills east of Ypres. That done the other striking force, the 4th Army, was to work forward along the coast keeping in touch with the fleet off the Belgian shore.
The affair at Messines was over by 12 June, and it would have been well if the 5th Army had been pushed forward immediately; for the task before it was long and the five months left for field operations before the winter set in were none too much for the work in hand. But delays occurred, and it was not until the last days of July that a start could be made. While affairs were in suspense, the Germans, suspecting the intentions of their opponents, made a lunge at the 4th Army at Nieuport and drove a part of it to the west side of the Yser. It was not an important battle, but it took from the British a portion of their bridge heads on the east of the stream, which would have been serviceable if they had been called upon to carry out their portion of the orienal plan of campaign. During the month of waiting
the Allied artillery searched out the wealc spots in the enemy's line with the utmost care. Many times the trenches were drenched with gas, in the use of which the British had become expert. At 3:30 in the morning of 31 July the whole line from a point two miles north of Boesinghe to the Lys, a distance of 15 miles, broke into a crashing barrage behind which the French and British infantry rushed forward to the first lines of the enemy, taking them at once. They then charged the second lines which were talcen for the most part, though the resistance was hard in some parts. At the end of the day all the objectives of the French and the 5th Army had been won and in some cases they had been exceeded, while more than 6,000 prisoners had been talcen. It was a brilliant beginning and the army rested from its day's work in contentment. That night began four days of steady rain and the ground nimed into seas of mud. It was not until 16 August that it was possible to renew the battle. On that day a general attack was launched. It succeeded on the northern part of the line, but through the resistance of a formidable system of '1011 boxes* in the region along the Menim road and three miles north of it the advance was held up from the beginning, although there was desperate fighting and great expenditure of courage on both sides. Next day the rain re turned in torrents and there was a fortnight of steady downpour. It was a full month before the water receded into the streams and the ground became dry enough for waging battle.
Meanwhile, General Haig revised his method of fighting. For two vreeks he had encountered a new system of defense devised by General von Arnim: Holding his first line with only enough troops to disorganize an advancing line he massed his troops in the second line and threw them on the foe as they came into the zone of fire of the second line. In this way his counterattacks were made very effective. At the same time he placed his apill-boxes* in such positions that they completely raked the area of approach. By tlus means he repelled the British in their attacic of 16 Auhrust with heavy losses. It was a new fashion m fighting and became known as aelastic defense.* General Haig gave it careful consideration during the month of enforced idleness while he waited on the weather. The best thought of his officers was given to the machine-gun defenses. By a system of careful observation the apill-boxes* were located and marked on the map and high explosive shells were fired at them when the battle was renewed. In this way many of them were destroyed, while the air was so filled with the fumes of the explosives that the men inside were rendered unfit for fighting. Another way that proved effective was to approach the work behind a barrage and suddenly make holes in the barrage on each side of the apill-box,* allowing die infantrymen to gain the unpro tected rear where hand grenades quickly dis posed of the defenders.