At the suggestion of Captain Black the boys had made sheet-iron cases for their cameras and reels of film.
"Of course, if a shell comes your way that case won't be much protection," said the United States officer. "But shrapnel won't go through it."
Steel helmets were also given the boys to wear when they went on duty in the firing trenches, and they were told under no circumstances to leave them off.
"For even if there isn't any shooting from across No Man's Land," explained Captain Black, "a hostile aircraft may drop a bomb that will scatter a lot of steel bullets around. So wear your helmets and keep the cases on your cameras."
It was a week after this, during which time there had been several false alarms of a big German attack, that one evening as they were about to turn in after having given a moving picture show an orderly came up to Blake.
"You and your two friends will report to Captain Black at four o'clock to-morrow morning," said the orderly.
"We're going over the top," was the answer. "You may get some pictures then."
Charles Anderson hastily consulted a small book he took from his pocket.
"Looking to see what time the sun rises. I want to see if there'll be light enough to make pictures. Yes," he went on, as he found what he wanted in the miniature almanac, "we ought to be able to get some shots."
The gray wreaths of a fog that had settled down in the night were being dispelled by the advance heralds of dawn in the shape of a few faint streaks of light when Blake and his chums, wearing their steel helmets and with the steel-protected cameras, started from the farmhouse where they were quartered to report to Captain Black.
"All ready, boys?" the captain called. "We're going over the top at five-seven--just as soon as the artillery puts down a barrage to clear the way for us. You're to get what pictures you can. I'll leave that part to you. But don't get ahead of the barrage fire--that is, if you want to come back," he added significantly.
"All right," answered Blake, in a low voice.
He and his chums took their places in one of the communicating trenches, waiting for the American and the French soldiers in the front ones to spring up and go "over the top."
Every minute seemed an hour, and there were frequent consultations of wrist watches. Suddenly, at five o'clock exactly, there was a roar that sounded like a hundred bursts of thunder. The artillery had opened the engagement, and the moving picture boys, at last on the firing line, grasped their cameras and reels of film as the soldiers grasped their guns and waited for the word to go.