At some distance from this latter sentry stood four tents, in which, Papa Prim had declared, slept the reliefs of the guard.
"I see how we could get the sentry at the rear," Dick whispered, after a few minutes' silent survey.

"But it's at the front that we want to get in, and I don't see any way of creeping up on the front sentry without the rear sentry seeing us and firing.

That would give the alarm." "Then we've got to 'get' the rear sentry first ?" Tom asked, his lips at his chum's ear.
"That's it." "Nasty business, and double chance of losing the game." "It's the only way, Tom, unless your head is working better than mine." For some minutes Tom Reade studied.
"I guess it will have to be the rear sentry first," he conceded.
At that moment a small door at the rear of the hangar opened.
The two friends heard the noise, and judged by sound more than sight.
"Sentry!" said the man who had stepped outside, in a low voice.
"Herr Lieutenant!" responded the man.

"I am not locking the door, sentry.

I shall be back before long." "Very good, Herr Lieutenant." Passing to the front of the hangar this German aviation lieutenant waited until the sentry there had reached him, then delivered the same information, after which the aviation officer strode off briskly toward the troop camp that could be only vaguely seen in the distance.
"It sounds as if he intended to make a flight," whispered Dick uneasily.
"That wouldn't be so bad," Reade replied.