The half-dozen machines, too, stood waiting and motionless, except for the answering quiver that ran through them to their engines' beat. Down from the line the throbbing roll of the gunfire rose louder and heavier, with a new, an ugly and sinister snarling note running through it. The flat thudding reports of the nearer Heavies came at quicker and closer intervals, the rumble of the further and smaller pieces ran up to the steady unbroken roar of drum-fire. The wind was coming from the line and the machines were lined up facing into it, so that the pilots had before them the jumping, flickering lights which flamed up across the sky from the guns' discharge. Earlier, these flashes had blazed up in broad sheets of yellow-and orange-tinted light from the horizon to half way up the height of the sky, leaped and sank, leaped again and beat throbbing and pulsing wave on wave, or flickering and quivering jerkily for seconds on end, dying down, and immediately flaring up in wide sheet-lightning glows. Now, in the growing light the gun-flashes showed more and more faintly, in sickly pallid flashes. There was no halt or pause between the jumping lights now; they trembled and flickered unceasingly, with every now and then a broader, brighter glare wiping out the lesser lights. The pilots sat watching the battle lights, listening to the shaking battle thunder, and waiting the Squadron Commander's signal to go. The birds were chattering happily and noisily, and a lark climbed, pouring out long shrill bursts of joyful song; somewhere over in the farmyard beside the 'drome a cock crowed shrilly, and from one of the workshops came the cheerful clink-link, clink-link of hammers on an anvil. It was all very happy and peaceful--except for the jumping gun-flashes and rolling gunfire; life was very sweet and pleasant--unless one thought of life over there in the trenches, and what the next hour or two would bring. Everyone knew there was "dirty work" ahead. It was the first really big "show" the Squadron had been in; they had been in plenty of the ordinary O.P.'s (Offensive Patrols) and air-scraps, but this was the real big thing, a great battle on the ground, and a planned attack on the grand scale in the air, which was to sweep the sky of Huns ... and the gunfire was still growing ... and the lark up there was bursting his throat to tell them what a pleasant place the world was on this summer morning, with the raindrops fresh on the grass and the breeze cool in the trees.