It was a Confederate victory, and one of the most lopsided in the whole Trans-Mississippi war. Major General Richard Taylor (South), outnumbered across the theater, had concentrated his army against the head of Major General Nathaniel Banks’s (North) strung-out column and shattered it. The disproportion flips the usual Civil War arithmetic, where the attacker normally bleeds worse: here the attacker got off light. Taylor lost roughly 1,000 men, the figure reported by General Edmund Kirby Smith (South), the Confederacy’s Trans-Mississippi theater commander, since precise Confederate returns were never recorded, while Banks lost about double that and saw some 1,500 of his men marched off as prisoners. The defender’s line collapsed and was captured wholesale; the attacker counted his losses in the hundreds.

The rout did not run clean to Mansfield, and the reason is a fourth Union line. Two or three miles back down the road to the south, Brigadier General William H. Emory’s (North) fresh division of roughly 5,000 men of the XIX Corps (a corps being one of the big numbered chunks an army is split into, each holding several divisions), infantry who had not yet been in the fight, formed a new line across the road and the woods (the stand the Park Service files as Pleasant Grove). It helped that the wrecked element and the intact backstop were different corps: the XIII Corps at the column’s head had taken the worst of the rout, while Emory’s XIX Corps division came up unbloodied. Taylor’s pursuing Confederates, flushed and disordered from chasing a broken enemy two miles through timber, hit this unbroken wall around six o’clock and could not push through it. After more than an hour, nightfall ended the fighting; a Confederate try after dark to turn Banks’s flank came to nothing. Emory’s backstop is the only reason the catastrophe had a southern edge at all.

Brigadier General Alfred Mouton (South), killed leading the opening charge, was no outsider to this ground. He was a Louisiana native, born at Opelousas in 1829, the son of a former Louisiana governor, West Point trained before he resigned to become a civil engineer and a sugarcane planter, and wounded earlier in the war at Shiloh. He was also, in plain terms, an enslaver, a man who owned human beings and who had led a vigilante committee that drove free Black people out of his parish. He died about three miles from a Louisiana town, on Louisiana soil, defending the slave society his own wealth was built on, the cotton-and-cane economy this whole campaign was, at bottom, a fight over.

The morning after, Banks (North) fell back to Pleasant Hill. There, the next day, Taylor attacked again and was repulsed by Sherman (North)’s loaned veterans under Brigadier General Andrew J. Smith (North), a tactical Union win that Banks promptly threw away by retreating regardless, abandoning the drive on Shreveport. Those veterans were on loan only until the end of April, a borrowed clock that helped make the whole expedition too brittle to recover from a setback. Pleasant Hill, April 9, is its own battle; Mansfield had already decided the campaign, and Pleasant Hill only confirmed it. The expedition reversed course and withdrew toward Alexandria and down the river.

Every one of the campaign’s four aims died with it. No Shreveport. No U.S. flag planted in Texas. No 100,000 bales of cotton. No expanded pro-Union government. The cotton-speculation scandal followed Banks into a postwar congressional investigation and effectively ended his military career. The whole bungled expedition tied up tens of thousands of Union troops and, by some historians’ reckoning, may have stretched the war out by months.