This, for the moment, was a sulphurous crater, the fire-belching demons, invisible in the smoke.  Through the glass Jack could see the lines clearly—­or the smoke arising above them.  The enemy had been pushed back nearly two miles since he had left Colonel Sherman a few rods above the stone bridge.  The Union force, as marked by the veil of smoke, curved, about the foemen, a vast crescent, seven miles or more from tip to tip.  The bodies opposing were scattered like a gigantic staircase, with the angles of the steps confronting each other step by step.  But now the Union ranks at Jack’s feet rush forward; a group of riders are coming to the tree, and Jack descends hastily to meet the general.  He is again disappointed.  It is not McDowell.  At a loss what to do, he salutes one of the officers and states his case, recognizing, as he turns, General Franklin.

“I don’t see that you can do better than remain where you are, or, still better, push to the brow of that hill yonder and act as a picket.  In case you see any force approaching from this side, which is not likely, give warning.  Our cavalry ought to be here, but it isn’t.  If you are called to account when the battle is done, give me as your authority.  I take it your brigade will be around here pretty soon, if they make as rapid work all the way as they have made since eleven o’clock.  If the cavalry come, you can report to the nearest officer for assignment.”

CHAPTER XI.

THE LEGIONS OF VARUS.

The two free lances set out now, relieved of all responsibility, and determined to watch the open fields and woods to see that this part of the field was not surprised.  The hill to which the general had directed them was farther from the battle than they had yet been, but the work going on to the northeast showed that this would soon be the western edge of the combat if Sherman continued advancing.  They are soon on the hill, and Jack posts himself in a tree with his glass.  There is a lull in the quarter they have just quit.  The smoke rolls away, and now he can see streams of gray-coats hurrying to the edge of the plateau, where, two hours before, he had encountered Porter’s brigade.  Can it be possible that Porter’s troops do not see these on-rushing hordes?  They are moving on the right point of the crescent, and unless the Union commander is alert they will break in on the back of the point; for Jack, without knowing it, was virtually in the rebel lines—­that is, he was nearer the rebel left flank, the foot of the long, bow-shaped staircase, than he was to the tip of the Union crescent.