The Germans began to shell Bethune, which was within the allied lines about eight or nine miles west of La Bassee. An hour later, in the neighborhood of nine o'clock, following up heavy artillery fire, the Fifty-sixth Prussian Infantry and the Seventh Pioneers advanced south of the canal, which runs eastward from Bethune, where the British line formed a salient from the canal forward to the railway near Cuinchy, and thence back to the Bethune and La Bassee road where the British joined the French forces. This salient was occupied by the Scots and the Coldstream Guards. The Germans were obliged to advance by the road, as the fields were too soft for the passage of the troops; even the roads were in a terrible condition, deep ruts and thick, sticky mud greatly retarding the onward march of the German forces. But the Allies fared little better in this respect. In fact the entire engagement was fought out in a veritable sea of mud and slush. Well-directed artillery fire by the Germans blew up the British trenches in this salient, and the Germans at once penetrated the unsupported British line. The Germans also had the advantage of an armored train, which they ran along the tracks from La Bassee almost into Bethune, sufficiently close to throw considerable shell fire into this town. The Germans advanced in close formation, throwing hand grenades. They came on so rapidly and with such momentum that the Guards, trying in vain to stem the tide with the bayonet, were overwhelmed, and the British, in spite of desperate resistance, were forced back step by step. At some points the distance between the trenches was so small that it was utterly impossible to stop the onrush from one trench to the other. The Germans swept and broke through the British lines, treading their fallen opponents under foot as they advanced. At this point the British turned and fled, as there was no hope of successful resistance. As the great momentum forced the German advance through the allied lines into the open field beyond and was joined by a heavy column, which had debouched from the vicinity of Auchy, British guns opened a murderous fire and inflicted terrible slaughter upon these ranks. The Coldstream and the Scots Guards retreated to their second line of defense, where they joined others of their command held in reserve there. Once again they turned to meet the oncoming Germans, and again were forced to give way, leaving the Germans in possession of all the ground previously gained. The remnants of the Guards retreated until they were met by the London-Scottish regiment sent to reenforce them. Here they halted while a counterattack was being organized by the First Royal Highlanders, part of the Camerons, and the Second King's Rifle Corps which also came up.