After keeping its high level for some distance, Cemetery Ridge falls away for the space of several hundred yards, to rise again by a gradual slope to a rugged, bowlder-strewn, rather thinly wooded hill, called Little Round Top, which finely overlooks all that part of the field. Thus, what Culp's Hill was to the right Little Round Top was to the left of the Union position--at once bulwark and warder. Still beyond Little Round Top, out across a little valley opening a passage between them, rose a much loftier eminence, called Big Round Top. Strangely enough, neither of these commanding hills was occupied in the morning; for though Geary's pickets lay out before Little Round Top all night, they had been called in at daybreak, when the division itself marched off to rejoin its corps at Culp's Hill.[54] Most unfortunately, too, the Union cavalry was no longer there to watch the enemy's movements in this quarter and promptly report them at headquarters, as Meade himself had sent off Buford to the rear of the army.[55] In military phrase, the whole Union left was in the air. Up to nine in the morning, therefore, this part of the field where Lee designed to strike his most telling blow was anybody's position, so far as the dispositions for its defence are concerned; but at that hour Sickles[56] began deploying the Third Corps toward Round Top. Presently two of his brigades that had been left behind were seen marching down the Emmettsburg road, under fire from the enemy's skirmishers;[57] so giving them sharp notice that this road was no longer open. Little Round Top, however, still remained unoccupied, save by a handful of men belonging to the Signal Corps of the army. [Sidenote: Dangerous Marching.] The men of the Third Corps watched the march of their comrades in breathless expectation of hearing the enemy's cannon open upon them, or of seeing some body of infantry suddenly pour a withering volley into them from the cover of the woods. But whether the enemy were too much confounded by the very audacity of the thing, or purposely refrained from hostilities that might expose and frustrate their own movements, now in progress under the mask of these very woods, neither of these things happened. These two lost brigades of Kearney's Peninsula veterans simply closed up their ranks, and strode steadily on between the two armies, without quickening their pace. In vain Sickles looked round him for some cavalry to escort them into his lines. There was no longer a single sabre on the ground. [Sidenote: Sherfy Place.] [Sidenote: The Cross-road.]