The story of that very rapid advance is merely one of succeeding dates. By the 17th the front was at Tirlemont, by the 19th it was across the Dyle and running thence south to Wavre (the first army), the second army continuing south of this with a little east in it to a point in front of Namur. On the 20th there was enacted a scene of no military importance (save that it cost the invaders about a day), but of some moral value, because it strongly impressed the opinion in this country and powerfully affected the imagination of Europe as a whole: I mean the triumphal march through Brussels. Far more important than this display was the opening on the evening of the same day, Thursday, August 20th, of the first fire against the eastern defences of Namur. This fire was directed upon that evening against the two and a half miles of trench between the forts of Cognelée and Marchovelette, and in the morning of Friday, the 21st, the trenches were given up, and the German infantry was within the ring of forts north of the city. The point of Namur, as we shall see in a moment, was twofold. First, its fortifications, so long as they held out, commanded the crossings both of the Sambre and of the Meuse within the angle of which the French defensive lay; secondly, its fortified zone formed the support whereupon the whole French right reposed. It was this unexpected collapse of the Belgian defence of Namur which, coupled with the unexpected magnitude of the forces Germany had been able to bring through the Belgian plain, determined what was to follow. Once Namur was entered, the reduction of the forts was not of immediate importance, though it was immediately and successfully achieved. For the German business was not here, as at Liége, to grasp a railway within the zone of the fortifications, but to destroy the buttress upon which the French depended for their defensive position, and to prevent the French from holding the crossings over the two rivers Sambre and Meuse at their junction. With this entry of the Germans into Namur, their passage of the lines upon Friday, August 21st, their capture of the bridgeheads on Saturday, August 22nd, we reach the beginning of those great operations which threatened for a moment to decide the war in the West, and to establish the German Empire in that position to attain which it had planned and forced the war upon its appointed day. It behoves us before entering into the detail of this large affair to see the plan of it clearly before our eyes. * * * * * I have already described that general conception underlying the whole modern French school of strategy for which the best title (though one liable to abuse by too mechanical an interpretation) is "the open strategic square."