As described previously, even though overall the US had more men in the campaign, Taylor enjoyed a numerical advantage at the moment he attacked at Mansfield. As a result Taylor was able to overwhelm the US front line, turning it in on itself and driving it back. So for Taylor, not much went wrong that day (He did lose about 1,000 men, including around 1/3 of Mouton’s division as well as Mouton himself). But for the U.S. side it was a disaster. What had gone wrong?
There was consensus among U.S. commanders that defeat occurred because at the point of contact the Confederate forces outnumbered the U.S. forces. However, in their testimony before Congress’s Joint Committee on the Conduct of the War there was revealed a split in opinion as to whether the U.S. force at the front should have been larger or smaller.
The idea that the U.S. forces should have been larger is easy to grasp — if the problem was that the Confederates had a numerical edge, then the way to counter that is to have more numbers. If the 3rd Division of the 13th Corps could have reached the front line sooner and if the 1st Division of the 19th Corps had been close behind, then Taylor could have been driven back instead of the other way around. This view blamed the outcome on the separation between units during the march. Thus the fault was with General Franklin, who managed the march.
The idea that the U.S. forces should have been smaller is based on the view that no battle should have been fought that afternoon. This view blamed the outcome on the decision to take a stand at that location at that time. If only a small cavalry contingent had been present, the front could have been more dynamic, pulling back if pressed. In this way, U.S. forces could avoid a battle they weren’t ready for. But by bringing infantry to the front, the position became fixed and battle could not be avoided. In this view the fault was with General Banks who directed that the position be held and infantry added.
So who was right? Both views have their positives and negatives. The point of advancing was to engage the Confederates and Banks had specifically directed Franklin to manage the march so that he would be ready to fight once the opponent was found. But movement along a single road through dense woodland is problematic and until the line could be tightened up, the U.S. was not ready for battle. However, the real problem was not which one was a better choice but with the fact that there was a divergence in view between the overall commander (Banks) and the commander directing the movement (Franklin). They were not on the same page when it came to operational decisions. To me this is Banks biggest failure in leadership: he did not have the confidence of his key subordinates (specifically Franklin and A.J. Smith) and, rather than working as a team, there was friction between them.
But when you really get down to it, what really went wrong for the U.S. was being there at all. Win or lose in the battle of Mansfield, the U.S. was already losing the campaign.
As mentioned previously, the Confederates had concentrated forces in northwestern Louisiana such that Taylor had over 12,000 at the battle and 5,000 close at hand (the Missouri and Arkansas infantry divisions). In addition, there was another approximately 5,000 not far off: Woods Texas cavalry brigade, Parsons Texas cavalry brigade, and the 3rd Texas Infantry would arrive over the next few days from Texas; Hawthorn’s Arkansas brigade was on the way to Shreveport from Arkansas; General Liddell had a brigade of Louisiana Cavalry on the north side of the Red River; and in Shreveport there were miscellaneous other troops such as the 1st Trans-Mississippi Cavalry, 6th Louisiana cavalry, Louisiana Heavy Artillery/Siege Battalion, and the Engineer Battalion. This concentration gave the Confederates the strength to challenge and delay the US advance. In addition, the Confederates had developed defenses at Shreveport and along the river which together with the dropping water level neutralized the U.S. fleet.
The U.S. operation was constrained by a timetable and thus could not afford a lengthy campaign. There was also doubt if the US could even have held Shreveport. Assessing the situation at the end of the campaign, General Canby wrote “It would require a force equal to the operating army to keep open its communications.” In testifying before Congress, General Emory stated that Shreveport “could not have been held and communications kept up by the Red River, except by an immense army”. Colonel Charles Dwight, inspector general of the 19th Corps, testified that “I think we would have been worse off at Shreveport than we were where we were checked. I think the further we went the worse off we would be.”
In conclusion, the Confederates had succeeded in concentrating their forces and had made good use of geography while the U.S. had pushed deep into Confederate territory on an unworkable timetable with inadequate logistical support. Thus, while the battle of Mansfield was tactically successful, Confederate success in the campaign was already assured due to operational and strategic factors.