Three fresh divisions and fifteen companies of _stosstruppen_ (shock-troops, or special troops of assault) were to lead the attack with light machine-guns, _minenwerfer_, signalmen, miners, sappers, gasmen, grenadiers, stretcher-bearers, and artillery patrols. Twelve “booty-squads” and twelve “destruction-squads” each composed of an officer and thirty-two men were to follow the _stosstruppen_. Arrangements had been made with a view to removing the captured guns. They had prepared for a formidable discharge of a new gas by a six-company regiment of sappers. The gas attack was to be launched for a quarter of an hour. A very strong artillery preparation was to follow, after which the _stosstruppen_ were to rush forward. The aviation was to play an important rôle, and the attack was to be made with the aid of all the means of liaison known: dispatch-runners, telephonists, optical signals, carrier-pigeons, luminous rockets, and wireless telegraphy. [Illustration: West of Ailles May 4, 1917--Noon] Orders had been given to bring back as many French gas-victims as possible, with a view to studying the effects of the new product. On the 20th of November, 1917, the third English army, by a successful surprise attack, penetrated into the German lines to a great depth and on a large front. This operation, prepared in the greatest secrecy, was carried out without the usual assistance of the artillery or barrages. The infantry attacked under the protection of numerous tanks which destroyed the wire entanglements and the most important obstacles. We do not think that this method will henceforth become a rule. Before launching this attack, the British Commander must have been informed by his aviation, or by some other means, that the German Front was lacking in artillery and infantry and he must very cleverly have taken advantage of this momentary situation. Must we conclude that the rules of preparation of attack, as stated above, will not be applied hereafter? It is very doubtful, in view of the fact that the Germans have prepared in France too many lines of defence, one behind the other. This English victory, however, shows that the High Command, whenever in possession of information warranting the hope of success, will have to combine regularly prepared attacks with surprise attacks on points where the German effectives happen to be reduced. The success of this operation on the Cambrai Front proves that, however strong a position may be, however numerous its wire defences, it will always be possible to take it when not protected by a sufficient force of artillery and infantry.