"The general commanding directs that you close up on Reynolds as fast as possible; and support him."
On the afternoon of September 20, 1863 Union Brigadier General Thomas John Wood committed an act under orders that directly led to the defeat and near destruction of the Army of the Cumberland. He followed orders even though he knew that it would cause problems that could be avoided. He did this mainly out of spite. Wood was aware that there were Confederates in his front, what he was not aware of was that they were about to attack. When Wood pulled his division out of line he did so just moments before Confederate Lieutenant General James Longstreet launched his assault. With no Union defenders in their way the Confederates easily made their way into the Union rear. The Union army put up a brief defense on their right but soon all that was left of the Union army was Major General George Thomas' men on the army’s left. Thomas then conducted a masterful defense, stretching his lines along Snodgrass Ridge. At nightfall Thomas retired to Rossville. The next day he withdrew into Chattanooga where Major General William Rosecrans and the rest of the army was waiting. The Chickamauga campaign was over. There is no changing those events, however, it is interesting to wonder what might have happened if Wood had exercised the discretion that his rank accorded him.
This is not alternative history in that there will be no discussion of imagined events. This story will focus on the defensive possibilities of the ridge line that runs north from the Widow Glenn house site through Lytle Hill and along the western edge of Dyer Field and the Dyer Ridge defensive line. I do not believe this ridge line has a name, although it is technically a continuation of Missionary Ridge. I will use the designation Lytle Hill-Dyer Ridge. Rather than discuss fake charges against these defenses there will be a discussion of the defenses and only a guess as to what might have transpired differently there. The suspension of belief required for this discussion is that Wood would stay in position rather than fill an imaginary gap and create a real gap. There are many possible ways this fateful movement could have been prevented.
When we know all the circumstances of the order and its prompt execution it might seem a pretty big leap of faith to imagine a situation in which Wood decides to stay put and possibly anger Rosecrans again. It seems quite possible that Wood would have obeyed any order from Rosecrans due to the bickering between them, more on their strained relationship below. If their relationship had been better and Wood had felt like he had more discretion in obeying the order there were some very good reasons for Wood not to have instantly moved. In fact there are at least three reasons he should have stayed; the constant skirmishing of the morning, the fact that Wood knew there was no gap and that the order was written faultily.
Wood's withdrawal began the collapse of the Union army. It is possible to argue that the Confederates would have won the battle anyway, that Longstreet's attack would have succeeded due to the depth and strength of his column. It is also possible to argue that the Union could have held out long enough that Confederate General Braxton Bragg would withdraw. The Army of Tennessee had not achieved any decisive victories against the Army of the Cumberland. They had never forced them to abandon a battlefield in retreat as had happened in other battles in other theaters. In the two previous encounters that Bragg's army had attacked the Union army (commanded by Buell at Perryville and Rosecrans at Stones River), Bragg’s army had driven the Union from most of its positions but ultimately Bragg would decide to retreat. It was entirely possible that if Rosecrans could keep Bragg at bay for the rest of the day that Bragg would decide to retreat again. Those possibilities became mute when Wood received the fateful order.