"What in the world is the meaning of this?" Frank asked of Jack.
"Don't know," returned the lad, "but I guess I'd better join in."
He drew his revolver and fired several shots in the air.
"Seems to be expected of us," he said. "We don't want to disappoint them."
The German aircraft now headed straight for the city of Calais. Frank sent his machine speeding in the same direction. Then, just as it appeared they would fly directly above the city, the first German craft began to descend. The others did likewise and a moment or so later they all came to earth in the center of what Frank and Jack could see was a small army camp; and as they alighted from their machines, the lads saw that it was an Allied camp and not a German.
"Must be Calais," said Frank to Jack in a whisper. "Have we been mistaken? Are these French and British machines?"
"Well, it looks like it," returned Jack. "We'll keep quiet and let the other fellows do the talking."
A French officer now approached the pilot of the first aircraft.
"We heard the firing aloft a moment ago," he said. "Did you encounter the enemy?"
"We were pursued all the way from the German lines," was the reply.