The Germans sought to obviate this check to their activities by approaching on rafts on which were machine guns, from which attempts were made to pour an enfilading fire on the trenches. Thereupon the Belgian sharpshooters became especially active and exterminated the machine-gun crews before the Germans could take advantage of the position they had gained by using the rafts. Finally the waters subsided and the mud which remained dried. As soon as the ground became firm enough to support troops the Belgians became so active that the Germans desired more men, but their soldiers were also needed in many other sections of the western front, and for the time being none could be sent against the Belgians. Hence King Albert's troops continued to make progress. The Germans made an attack between Nieuport and the sea on May 9, 1915, but were repulsed. To the north of Dixmude the Belgians were violently attacked during the night of May 10, 1915, by three German battalions. They were repulsed and suffered large losses. On the night of May 16, 1915, the Germans threatened with complete envelopment by the successful attacks of preceding days, evacuated the positions which they had occupied to the west of the Yser Canal, and they gained nothing on the eastern bank. The Germans left about two thousand dead and many rifles when they were forced from the western bank. On the following night, May 17, 1915, the positions on the eastern bank were consolidated, and a German counterattack, which was preceded by a bombardment, was repulsed. The Germans gained a footing in the trenches to the east of the Yser Canal in an attack made on the night of May 20, 1915, but they were driven out and lost some of the ground they had held before making the attack. The Germans made a violent attack on the edge of the Belgian front at Nieuport in order to prevent the Belgians from aiding in the defense of Ypres, but the Belgians defended Nieuport with one army corps and made an advance on Dixmude with another corps, with the result that they assisted the Zouaves in taking the German bridgeheads on the western bank of the canal above Ypres. These bridgeheads were protected by forts manned by machine guns, and the approaches were commanded by heavy artillery fire, but defense was destroyed in the middle of May, 1915. The Germans concentrated their efforts against the Belgians at one point between Ypres and Dixmude. They bombarded the trenches, using bombs filled with poisonous gas. When they believed the Belgians had been overcome by the gas the German infantry charged. The Belgians, however, had kept their faces close to the ground, thus escaping most of the fumes from the shells. When the Germans arrived within easy range they were greeted with machine-gun fire to such an extent that the companies leading the charge were slain.