four o'clock in the morning
He walked back and forth a long time , and the air continued to thicken . A heavy fog was rising from the prairie , and it became so dense that he could no longer see the fires in the Mexican camp . Everything there was shut out from the eye , but he yet heard the faint noises . It seemed to him toward four o'clock in the morning that the noises were increasing , and curiosity took hold of him . But the sentinel on the left and the sentinel on the right were now hidden by the fog , and , since he could not confer with them at once , he resolved to see what this increase of noise meant . He cocked his rifle and stole forward over the prairie . He could not see more than ten or fifteen yards ahead , but he went very near to the Mexican camp , and then lay down in the grass .