Fortunately his chums of the trenches understood, and while some of them caught up the unconscious boys and started with them to the rear, others saved the moving picture machines.
And then, just as it seemed that the Germans would overtake them and dispose of the whole party, there came a rush of helmet-protected Americans who speedily dispersed those making the counter-attack, pursuing them back to the very trenches which they had left not long before.
The fight went on in that gas-infested territory, a grim fight, desperate and bloody, but in which the Allies were at last successful, though Blake and his two chums saw nothing of it.
"They're in a bad way," the surgeon said, when he examined them soon after Drew and his friends brought them in. "I don't know whether we can save them."
But prompt action, coupled with American ingenuity and the knowledge that had been gained from the experience of French and British surgeons in treating cases of gas poisoning, eventually brought the moving picture boys back to the life they had so nearly left.
It was several days, though, before they were out of danger, and by that time the French and Americans had consolidated the gains it cost them so much to make, so that the place where the three boys had been overcome was now well within the Allied lines.
"Well, what happened to us?" asked Joe, when he and his chums were able to leave the hospital.
"You were gassed," explained Private Drew, who had had a slight attack himself. "Didn't you hear me yelling at you to put on your helmets?"
"Yes, and we started to do it," said Blake. "But that stuff works like lightning."
"Glad you found that out, anyhow," grimly observed the soldier. "The next time you hear the warning, 'Gas!' don't stop to think, just grab your helmet. And don't wait longer than to feel a funny tickling in your nose, as if you wanted to sneeze but couldn't. Most likely that'll be gas, too. Cover your head when you feel that."