Though the antiaircraft guns, or "Archibalds," as the soldiers called them, were not especially effective except in keeping the flyers at such a height that it was not easy for them to make effective observations, a "Taube" was brought down at Pervyse, and near Ypres another was damaged on April 8. But on April 12 a German flyer inflicted some loss on the Allies' lines and escaped without being even hit. On the following day, presumably emboldened by that success, German aeroplanes threw flares and smoke balls over the British trenches east of Ypres, with the result that the soldiers of King George were subjected to a severe bombardment. All things considered, however, the Allies had ground for their belief that they more than held their own in the air. Afloat the Allies continued to maintain the supremacy which had been theirs. The French and British battleships held the left of the Allies' line. Their great guns proved their effectiveness on the Germans who were advancing from Ostend on Nieuport. They repeatedly bombarded the position of the kaiser's men at Westende, east of Nieuport. The Germans had trained one of their mammoth pieces of artillery against that town presumably because it held the sluices and locks which regulated the overflowing of the Yser territory. If the means of flooding the land could not be seized, the next best thing to do was to wreck them. The Belgians, in the meantime, assumed the offensive, their left being protected by the Allied fleet and the French forces in the neighborhood of Nieuport. These troops captured one of the smaller forts east of Lombartzyde on March 11, 1915. There was also fighting at Schoorbakke, north of the Yser loop, where the German trenches were shelled by French artillery. This was on the eastern border of the inundated section. After destroying the German front in the graveyard at Dixmude, the French artillerists battered a German convoy on its way between Dixmude and Essen on March 17, 1915. By March 23 the east bank of the Yser held a Belgian division. In fact, from Dixmude to the sea the Allied troops were advancing. The Germans, however, advanced south of Dixmude. On April 1, 1915, they shelled the farms and villages west of the Yser and the Yperlee Canals, and took the Driegrachten farm. Thereupon the Germans crossed the canal with three machine guns. Their plan was to proceed along the border of the inundated district to Furnes. But the French balked the plan by shelling the farm, and the Belgians finished the work by driving the Germans back to Mercken on April 6, 1915.