I saw the beginning of the battle, and watched the frightful gun-fire until darkness and dense banks of smoke blotted out this vision of the mining cities in which men were fighting through bursting shells. That beginning was a terrifying sight, and a sense of the enormous tragedy of the world in conflict overwhelmed one's soul, because of the strange atmospheric effects, and that most weird mingling of storm and artillery, as though the gods were angry and stirred to reveal the eternal forces of their own thunderbolts above this human strife. Just in front of where I crouched in a shell-crater was Swallows' Wood, or the Bois d'Hirondelle, and beyond that La Coulotte, which the Canadians had just taken, and a little way farther the long straggle of streets which is Avion, leading up to Lens, with its square-towered church and high water-towers and factory chimneys. Straight and long, bordered by broken trees, went the Arras-Lens road, on which any man may walk to a certain rendezvous with death if he goes far enough, and I saw how it crossed the Souchez river by the broken bridge of Leauvette, from which the Canadians were going to make their new attack. A gleam of sunlight rested there for a while, and the little river was a blue streak this side of Avion. But the sky began to darken strangely. The air was still and hushed. A blue dusk crept across the landscape. The trees of Hirondelle Wood and the towers of Lens blackened. Far behind Vimy, old ruins--of Souchez and Ablain-St.-Nazaire--were white and ghostly. One of my companions in a shell-hole looked up and said: "Is the 'good old German God' at work again?" Other powers were at work. Huge shells from our heavy howitzers, now away behind us, passed overhead with a noise such as long-tailed comets must have. I watched them burst, raising volumes of ruddy smoke in Avion and Lens. To the right of Lens by Sallaumines there was some other kind of explosion, rolling up and up in big, curly clouds. In the still air there was the drone of many engines. The darkening sky was full of black specks, which were British aeroplanes flying out on reconnaissance over Lens and Avion. "O brave birds!" said a friend by my side, waving up to them. German shrapnel puffed about their wings, bursting with little glints of flames, but they flew on. It was then just seven o'clock. Our guns had almost ceased fire. There were strange sinister silences over all the battlefield, broken only by single gun-shots or the high snarl of German shrapnel or the single thud of a German crump. It was almost dark. The blue went out of the little Souchez river. Lens and Avion were in gulfs of blackness. A long rolling thunderclap shook all the sky, and flashes of lightning zigzagged over the Vimy Ridge, whitening the edges of its upheaved earth. The sky opened, and a storm of rain swept down fiercely.