Brialmont meant the various forts which defended Liége to be joined to each other by means of trenches and gun-pits, so as to prevent the enemy from rushing in between them at night or in misty weather. Unfortunately these lines of trenches were never completed. Nevertheless the position was thought to be one of the strongest in Europe. Five years ago a German general reported that his army had no gun strong enough to destroy one of the Liége forts, and added that such a gun must be made. We shall soon see that his advice was taken. * * * * * Turn to the map on page 226, and find the position of Aix-la-Chapelle,[187] which the Germans call Aachen. It is an important military centre of Germany, and is on the great railway route from Berlin to Paris. Follow the railway, and you will see that it curves round by way of Verviers, and then runs along the valley of the Vesdre to Liége. As the crow flies, Aix-la-Chapelle is only twenty-five miles from Liége. About the same distance south of Aix-la-Chapelle is Malmedy,[188] the German Aldershot, where several army corps are always in training. About three years ago the Germans persuaded the Belgian Government to let them make a branch line connecting Malmedy with the Belgian railway system at the little town of Stavelot.[189] * * * * * On the morning of Tuesday, 4th August, German advance guards suddenly seized Stavelot and began to march upon Liége from the south-eastward. At the same time, troops from Aix-la-Chapelle crossed the frontier and occupied Verviers.[190] Picked soldiers in motor cars were also hurried across the plain towards Visé.[191] The invasion of Belgium had begun. Before the vast armies of Germany could advance, Liége must be captured. The eastern forts of the city commanded all the railways, and all the roads but one, and that was the road leading from Aix-la-Chapelle to Visé. The Germans expected little opposition from the Belgians, and believed that they had an easy task before them. There were no Belgian soldiers on the frontier to oppose them, and they advanced unmolested. They tried to make friends with the people in the towns and villages through which they passed; but many of the townsfolk and villagers at once fled by road and rail into Holland or towards Brussels. [Illustration: Diagram of a Liége Fort.]