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.