The sweeping advance of the Allied infantry, preceded by French cavalry which performed wonderful work in carrying out charges, left Lille and the mining and manufacturing districts of Tourcoing, Roubaix, and Tournai in a salient that was growing deeper every hour and which the Germans could not possibly hold for long. In the region of Thourout the Allies encountered intense opposition. The struggle was here from house to house and street to street, and the casualties were heavy on both sides. The Germans had posted machine guns in the windows of the dwellings and in the cellars, firing streams of bullets into the advancing Belgians, but were unable to force them back. The troops of King Albert fought with a fierce determination to wreak revenge on the despoilers of their country, and nothing could withstand the cold fury of their onslaught. To the northeast of Courtrai they stormed and captured Bavichove and on the north Andoye and Cachten. [Illustration: Battle lines and operations on the Western Front in 1918, including German territory held by the Allied armies of occupation.] The capture by the British of Linselles along the Lys placed the Germans in the salient in a highly precarious position as the Allies pressed forward, and it was inevitable that they must soon retire to save themselves. Outside Courtrai the infantry made an advance of about three miles. Here they were forced to crush stubborn enemy attacks, the Germans having received orders to hold on to the last. Very few of their machine gunners who tried to hold up the Allied advance managed to escape. From the Thielt positions, where the French cavalry, owing to the hardness of the ground and roads, were able to operate freely and consequently worry the Germans, the Holland border was less than twenty miles. It was through this gap that the Germans throughout the whole Belgian coast system must retire if they were to save themselves, provided that the Allies continued to advance. Every yard of ground gained by the Allies in this area lessened the Germans' chances of escape by narrowing the gap through which they must go. The Allied offensive in Flanders did not spend itself for nearly three days, the German retreat becoming more and more disorderly so that at some points it was a veritable rout. The entire Belgian front from the south was in constant movement. From Ostend and that section of the Belgian coast the Germans fled precipitately. British naval forces and Belgian aviators entered Ostend on October 17, 1918, where they were received with cheers and tears of joy by the inhabitants.