The belief in the supposed superiority of the German artillery was so shaken in the minds of the General Staff as a result of the fighting on the Neuve Chapelle front that they shortly after issued an order to try a series of experiments on animals with asphyxiating gases. CHAPTER XV OPERATIONS FOLLOWING NEUVE CHAPELLE There was very little activity on the western front after the fighting at Neuve Chapelle and St. Eloi until the beginning of a renewal of the campaign between La Bassee and the sea. The importance of success in this region was appreciated by both sides. The Germans north of the Lys planned to cross the Comines-Ypres, Yperlee, and Yser Canals, capture Ypres, take all of the ridge of the Mont-des-Cats, and then continue west and take Dunkirk, Calais, and Boulogne. The Allies in their plan included an advance south of the Lys on two sides of Lille, the taking of the Aubers Ridge, and the turning from the north the German salient at La Bassee. This much of the Allies' plan was to be executed by the British. The work of the French was to drive the Germans from the vicinity of Lens and threaten La Bassee from the south and west. The reasons for making these plans are obvious. The German salient was a source of much danger to the joining of the British and French armies, and the possibility of the Germans forcing their way through to Boulogne meant a possibility of a cutting off of the entire British army and the French and Belgian forces between Ypres and the sea near Nieuport. However, if La Bassee was isolated and the Aubers Ridge taken by the British, the chances that the Germans could retain Lille were materially lessened; and if the British got Lille they might start to drive their enemy from Belgium. During the lull in the fighting on land, to which reference has been made, there was much activity in the air. Reconnaissances and raids were of almost daily occurrence. A Zeppelin dropped twenty bombs on Calais, slaying seven workmen at the railroad station on March 18, 1915. Three days later another, or possibly the same Zeppelin, flew over the town, but this time it was driven away before it could do any harm. "Taubes" bombarded the railroad junction of St. Omer and made a similar attack on Estaires on March 23. Four days after another attack was made on Estaires, and on the same day, March 27, the German airmen did some damage to Sailly, Calais, and Dunkirk. The next day a "Taube" made an attack on Calais, Estaires, and Hazebrouck. A Zeppelin closed the month's warfare in the air for the Germans by making a dash over Bailleul.