It was merely a hole dug underground, earth, supported by timbers, forming the floor, ceiling and sides, while the entrance was made of a plank door, with cracks large enough to show that a passage ran outside—­a passage along which men passed with a frequency which seemed to indicate that escape would be exceedingly difficult.

“Well, we’ve just got to make the best of it,” said Blake.  “I’m going to get what rest I can.”

It could not be much at best, for there was no furniture in the cavelike cell.  The boys curled up in corners—­fortunately it was not cold—­and thought over their situation.  That it was very desperate they all admitted.

That night was like a bad dream to them.  At times they dozed off in light slumber, but, as far as they knew, their captors did not so much as look in on them.  They did not know, of course, when morning came, but they judged that the sun had risen when, after several hours of waiting, a tin can of water and some food was thrust in to them.

“And I’m hungry enough to eat even German sausage,” announced Macaroni, as he inspected the food.  It was coarse but satisfying, and the boys felt better when they had eaten it.

Later came a squad of Germans, one of whom spoke enough English to order Blake and his chums to follow them.  They were led out of the dungeon, along a covered underground passage, and then they suddenly emerged into daylight.

“Well, it’s a comfort to be able to see,” remarked Joe, as he and his companions looked about.

Without a word as to where they were to be taken, the boys were marched along, and, for a moment, they feared they were to be the victims of a firing party.  But a turn in the course showed them just ahead a group of buildings about which could be seen some German officers.

“Evidently we’re going to be questioned by some one in authority,” suggested Blake.  “Well, that looks more hopeful.”

They were at the very edge of an enclosure containing the official headquarters of that part of the German army, and the leader of their squad was about to reply to the challenge of the sentinel when a curious sound was borne to the ears of the boys.  It was like a fast motor operating at some distance.

“What’s that?” asked Charlie.

As if by a common impulse they all looked up, for the noise seemed to come from above, and they saw dotting the blue sky many small, black specks.

“Aeroplanes!” cried Blake.

The Germans had seen the objects in the air at the same time, but on them the sight produced quite a different effect from that made on the boys.

In an instant all thought of guarding Blake and his chums seemed to have been forgotten.  Their escort ran to one side.  The sentries on duty before the official headquarters hastened away, and some of the elaborately gold-laced officers ran within the buildings.

A moment later a number of soldiers could be observed some distance away manning a battery of guns, the muzzles of which pointed upward.