five o'clock exactly
`` 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 . The earth beneath them seemed to rock with the concussion of the big guns . Not a man of the American and French forces that were to attack the Germans had yet left the protecting trench .