We can best grasp the immensity of the struggle by attempting to grasp the immensity of the battleground. Such a task is for the imagination only, for the soldier saw only his little area, and no man’s first-hand experience could cover all the many fields. An observer on some altitude in the north, like the Hill of Cassel, on some evening in September 1918, could look east and note the great arc from the dunes at Nieuport to the coalfields about Lens lit with the flashes of guns and the glare of star-shells, and loud with the mutter of battle. That was a line of 50 miles—far greater than any battlefield in the old wars. Had he moved south to the ridge of Vimy he would have looked on another 50 miles of an intenser strife. South, again, to Bapaume, he would have marked the wicked glow from Cambrai to the Oise. Still journeying, from some little height between the Oise and the Aisne he would have scanned the long front which was now creeping round the shattered woods of St. Gobain to where Laon sat on its hill. From the mounts about Rheims he might have seen Gouraud’s battle-line among the bleak Champagne downs, and from a point in the Argonne the trenches of the Americans on both sides of the Meuse, running into the dim wooded country where the Moselle flowed towards Metz. Past the Gap of Nancy, and southward along the scarp of the Vosges, went the flicker of fire and the murmur of combat, till the French lines stretched into the plain of Alsace, and exchanged greetings with the sentinels on the Swiss frontier. Such a battle-ground might well have seemed beyond the dream of mortals, and yet it was but part of the whole.