They contemplated that Sherman's column, which was arriving by the north bank of the Tennessee, should cross the river on a pontoon bridge just below the mouth of Chickamauga Creek and carry the northern extremity of Missionary Ridge as far as the railroad tunnel; that the Army of the Cumberland -- the centre--should co-operate with Sherman; and that Hooker with a mixed command should continue to hold Lookout Valley and operate on our extreme right as circumstances might warrant.

Sherman crossed on the 24th to perform his alloted part of the programme, but in the meantime Grant becoming impressed with the idea that Bragg was endeavoring to get away, ordered Thomas to make a strong demonstration in his front, to determine the truth or falsity of the information that had been received.

This task fell to the Fourth Corps, and at 12 o'clock on the 23d I was notified that Wood's division would make a reconnoissance to an elevated point in its front called Orchard Knob, and that I was to support it with my division and prevent Wood's right flank from being turned by an advance of the enemy on Moore's road or from the direction of Rossville.

For this duty I marched my division out of the works about 2 p.m., and took up a position on Bushy Knob.

Shortly after we reached this point Wood's division passed my left flank on its reconnoissance, and my command, moving in support of it, drove in the enemy's picket-line.