He knew that to save their lives he must get their helmets on; for a few breaths of the gas will not kill.  But they will disable a person for some time, and a little longer breathing of it means a horrible death.

And so, working at top speed, the soldier, now himself protected from the fumes, though he had breathed more of them than he liked, labored to save his friends.

Suddenly a new terror developed, for, wearing their own helmets which made them look like horrible monsters out of a nightmare, the Germans charged against the French and Americans, whom they hoped to find disabled by the gas.

“Here they come with blood in their eyes if I could only see it!” mused Private Drew, as he finished fastening the helmet on Charles Anderson, having already thus protected Joe and Blake.  All three boys were now unconscious, and what the outcome would be the soldier could only guess.

“But there won’t be any guesswork if I leave ’em here for the Huns,” he reasoned.  “I’ve got to help ’em back—­but how?”

The Germans, in a counter-offensive, were striving to regain some of the lost ground, and, for the moment, were driving before them the French and American forces.  Back rushed the advance lines to their supporting columns, and Drew, seeing some of his own messmates, signaled to them, for he could not talk with the helmet on.

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?”