Von Arnheim laughed pleasantly.

“It’s fair of you to give us warning of your intentions,” he said, “but I don’t think you’ll have much chance.  You must get ready to start at once.”

“I take it,” said John, “that our departure means the departure of the German army also.”

Von Arnheim opened his mouth to speak, but he closed it again suddenly.

“It’s only a deduction of mine,” said John.

Von Arnheim nodded in farewell and hurried away.

“Now I’m sure,” said John to Fleury a few minutes later, “that this army is going to withdraw.”

“I think so too,” said Fleury.  “I can yet hear the fire of the cannon on either flank and it has certainly moved to the east.  In my opinion, my friend, both German wings have been defeated, and this central army is compelled to fall back because it’s left without supports.  But we’ll soon see.  They can’t hide from us the evidences of retreat.”

The prisoners now marched in a long file in the moonlight across the fields, and John soon recognized the proof that Fleury was right.  The German army was retreating.  There were innumerable dull, rumbling sounds, made by the cannon and motors of all kinds passing along the roads, and at times also he heard the heavy tramp of scores of thousands marching in a direction that did not lead to Paris.

John began to think now of Lannes.  Would he come?  Was Weber right when he credited to him a knowledge near to omniscience?  How was it possible for him to pick out a friend in all that huge morass of battle!  And yet he had a wonderful, almost an unreasoning faith in Philip, and, as always when he thought of him, he looked up at the heavens.

It was an average night, one in which large objects should be visible in the skies, and he saw several aeroplanes almost over their heads, while the rattle of a dirigible came from a point further toward the east.

The aeroplane was bound to be German, but as John looked he saw a sleek shape darting high over them all and flying eastward.  Intuition, or perhaps it was something in the motion and shape of the machine, made him believe it was the Arrow.  It must be the Arrow!  And Lannes must be in it!  High over the army and high over the German planes it darted forward like a swallow and disappeared in a cloud of white mist.  His hair lifted a little, and a thrill ran down his spine.

He still looked up as he walked along, and there was the sleek shape again!  It had come back out of the white mist, and was circling over the German planes, flying with the speed and certainty of an eagle.  He saw three of the German machines whirl about and begin to mount as if they would examine the stranger.  But the solitary plane began to rise again in a series of dazzling circles.  Up, up it went, as if it would penetrate the last and thinnest layer of air, until it reached the dark and empty void beyond.