At length, fearing to lose his target by longer delay, for the first train was now abreast of the tiny hamlet of Beaumetz, and nearing the junction and the bridge-head at Velu, he threw out the signal for the attack.
A smoke bomb to the right and another to the left: that was the pre-arranged signal, and then, pulling over the joy-stick, down, down went Dastral, followed at regular intervals by the three other 'planes.
Down, down with a swoop, through the exhilarating rush of air, they went. All the engines had been shut off, and the pilots, with one hand on the joy-stick, and the other on the bomb release, waited almost breathlessly through those wild, thrilling seconds, while they fell with ever-gathering impetus, like a stone to the earth. Thus they went down to what seemed like certain death, while every instant during that mad dive seemed an age.
"Click! click!" went the little instrument that measured the altitudes. "Seven, six- five, three thousand feet," it tried to say, but its voice could not be heard.
At two thousand feet Dastral pushed back the joy-stick, and flattened out. His comrades did the same, all except Franklin in the last 'plane, who had trouble with his control wires and flattened out only at five hundred feet. Another five seconds would have dashed him to death. He was game, however, and though his face blanched, and his heart stayed its beating for an instant, he was soon climbing again to rejoin his comrades.
They had been seen now, for the smoke bombs had first given them away. The commandants of the German communications were hotly engaged on the telephone wires, reporting to headquarters and to the nearest aerodromes the presence of the intruders, and demanding that Himmelman and his comrades should come at once to deal with the sky-fiends.
The engine-driver of the first train also had seen the danger that threatened, and, putting on all speed, he tried foolishly to get away from the air peril. Velu was scarcely a mile distant, and there at least he could find some protection, if only in the "Archies."
But he was too late. When Dastral flattened out at two thousand feet he was almost abreast of the train. A neck-and-neck race commenced, but what chance has a heavily laden troop train, even though it has three engines, against a Sopwith which can do one hundred and thirty miles on occasion? It was like a race between a hare and a tortoise.
"Puff-puff-puff! Shriek!" went the train, but the scream of the siren was drowned in the whirr-r-r of the propellors racing alongside and just overhead, for the engines had been started again by the pilots as soon as they flattened out.
It was a matter of seconds now, for Dastral only waited until he had dropped down to one hundred feet. He was already in line with the engine, and directly above. Just ahead was the railway bridge, and the viaduct over the road leading into the village.