"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.
"They're going to fire at the airships!" cried Joe.
"And that means they are not German craft!" added Blake. "Boys, I guess the French and Americans are making an airship raid on Mr. Fritz this morning, and maybe it'll be a good thing for us. Let's hunt cover!"
CHAPTER XXIV
BURIED ALIVE
Even as Blake and his chums looked about for some place of refuge, the firing of the German anti-aircraft guns began. These weapons, designed especially for shooting straight up and sending shrapnel shells to a considerable height, were rapidly manned and fired by crews that seemed to be in readiness for just such danger.