"John, club your automatic, and hit that officer on the back of the head with it. Hit hard. Don't kill him, but you must knock him unconscious at the first blow. Carstairs and I will choke all but a spark of life out of the operator."
The three emerged from the stairway upon the flat portion of the roof where the wireless plant had been installed not more than four or five feet away. They made not the slightest sound as they stole forward, but even had they made it the two Germans were so deeply absorbed in their talk through the air that they would not have heard it.
John felt compunctions at striking an unsuspecting enemy from behind, but their desperate need put strength in his blow. The officer fell without a cry and lay motionless. At the same instant Wharton and Carstairs seized the operator by the throat, and dragged him down. He was a small spectacled man and he was only a child in the hands of two powerful youths. In a minute or two and almost without noise they bound him with strips of his own coat, and gagged him with a handkerchief. Then they stretched him out on the roof and turned to John's victim.
The man lay on his face. His helmet had fallen off and rolled some distance away, a ray of moonlight tipping the steel spike with silver. A dark red stain appeared in his hair where the pistol butt had descended.
The figure was that of a powerful man, and the set of the shoulders seemed familiar to John. He rolled him over, and disclosed the face of von Boehlen. Again he felt compunction for that blow, not because he liked the captain, but because he knew him.
"It's von Boehlen," he said, "and I hope I haven't killed him."
Carstairs inserted his hand under his head and felt of the wound.
"You haven't killed him," he said, "but you struck hard enough to make him a bitter enemy. The skull isn't fractured at all, and he'll be reviving in a few minutes. He's a powerful fellow, and we'd better truss him up as we have his friend here."
While Carstairs and Wharton were binding and gagging von Boehlen, John went to the railing about five feet in height that surrounded the central or flat part of the roof, the rest sloping away. The railing would hide what was passing there from the Uhlans below, but he wanted to take a look of precaution.
The men were riding up and down with their usual regularity and precision, watching every approach to the house, and making the ring of steel about it complete. This little wheel of the German machine was Working perfectly, guarding with invincible thoroughness against the expected, but taking no account of the unexpected. He came back to his comrades.