_Neutralization fire_ is made with asphyxiating shells. When the enemy’s batteries have been well pounded by destructive fire, the quickest way to put them completely out of action is to exhaust the gunners by neutralization fire and thus prevent them from serving the guns. Even with gas-proof masks the men very soon become exhausted on account of the difficulty they have in breathing through them. With this end in view, a bombardment with asphyxiating shells is kept up for several hours. For instance, at the time of the attack, near Craonne, on the 5th of May, 1917, one of our French army corps was faced by about one hundred and eighty German batteries of all sizes. Our destructive fire had terribly damaged those batteries; but the Germans, being undisturbed on their Eastern Front, could bring up fresh batteries at every moment, and were still able to oppose our advance towards the tableland of Craonne. On the whole length of our Front our artillery fired with asphyxiating shells, and a few hours afterwards, with the exception of four or five, all the German batteries had ceased firing. The importance of the use of asphyxiating shells may be very great. Recently in Champagne an asphyxiating shell of large size penetrated through a hole made by previous heavy shell-fire into a concreted German tunnel and exploded. This tunnel, which sheltered an important garrison, comprising two companies and many machine-guns, had already suffered heavily. Its exits were obstructed, but it was still holding out. All but one man were suffocated, surprised by the gas before they had time to put on their masks. A French surgeon, peering through the hole made by the shell and seeing no sign of life, crept into the corpse-filled gallery, and, after a brief reconnoissance, signalled to the nearest French troops that they could occupy it. It is not unusual to see, during the big attacks, the various artilleries established in eight and even more rows, occupying all the available vantage ground. The occupation of Hill 304 in August, 1917, is a striking example of the results of a thorough co-ordination of the different elements for the preparation of the attack and the capture of the position. Commencing with the systematic destruction of the enemy’s defences by several days’ continuous bombardment, accompanied by a most careful location of his batteries, with the help of all possible means of investigation (such as wireless telegraphy, photography, location of the guns by light and sound, interception of code signals, interrogation of prisoners, etc.), the guns of our counter-batteries, having duly apportioned these various objectives, succeeded on the morning of the 24th in neutralizing the fire of the German artillery, and exhausting the defenders of Hill 304.