By July 15, 1863, Gen. Joe Johnston’s “Army of Relief” suddenly found itself in need of relief of its own. Johnston’s impotent posturing during most of the Vicksburg Campaign had done little to alleviate Confederate misfortunes inside the besieged city, and following Vicksburg’s surrender, Federal commander Ulysses S. Grant decided to turn his full attention toward the pesky Johnston lurking vaguely in the Federal rear. Grant sent his pitbull, Maj. Gen. William T. Sherman, to deal with Johnston’s “Army of Relief” once and for all.
Sherman, with 40,000 men from his own XV Corps bolster by the IX and XIII Corps, moved eastward toward the Mississippi state capital, Jackson, where Johnston holed himself up with his 30,000 men. “Instead of attaching as soon as it came up, as we had been hoping, the Federal army intrenched itself, and began to construct batteries,” Johnston later wrote, somewhat defensively. Johnston’s own fortifications invited a siege.
Beginning on July 10, Sherman began to lob artillery shells into the city, hoping to demoralize and dislodge his adversary—but he quickly realized he was going to need more ammunition. “[W]e carried with us a good supply of ammunition, sufficient for an open field battle, but not for a siege,” Sherman reported; “and the moment I saw a siege was inevitable, I dispatched Captain McFarland, of my staff . . . to bring up a supply for such an event, and in the mean time our batteries were restricted in their use of ammunition so as to reserve at all times a sufficient quantity for an open field fight or a sally.”
Sherman estimated that his artillerists used about 3,000 rounds over the two days of July 12-13, “all of which did great execution.”
“I then only awaited the arrival of the ammunition train to open a furious cannonade on the town from all points of our line,” Sherman said.
Those supplies were soon in coming. On July 14, Johnston got wind that “a large train, loaded with artillery-ammunition, had left Vicksburg by the Jackson road,” he later wrote. “The enemy was observed to be actively employed in the construction of batteries on all suitable positions.”
Johnston summoned Brig. Gen. William “Red Fox” Jackson to lead a cavalry force into the Federal rear “to endeavor to intercept and destroy the ammunition-train. . . .” Jackson set out with a brigade of Texans, reinforced on the 15th by two additional regiments, and managed to get themselves into position for a strike.
And herein arises an interesting little puzzle.
“A man has just come into our lines from the rear, named A. Leroy Carter, representing himself to be of the Third Iowa Infantry, and just escaped from Jackson’s cavalry,” wrote IX Corps commander Maj. Gen. John Parke in a dispatch to Sherman.
The appearance of the Hawkeye was startling. His alibi? “This man states that he has been a prisoner since January 4, and detained because he was caught plundering,” Parke wrote. “He has since been kept under guard, and attached to the blacksmith’s or farrier’s department for Jackson’s division.”
Even more startling than Carter’s appearance was the news he passed along to Parke: “He says Jackson is headed this way, and the idea among the men was that he would attack our rear, so that they could make a sortie simultaneously on our front.” Carter even provided details troop strengths of Jackson’s force.
“Certainly a bold scheme,” Parke decreed.
While the details Carter offered Parke proved accurate—and his report did allow Federals to foil Jackson’s planned attack—Carter’s alibi seems more suspect. As a captive farrier in the Confederate cavalry, possessing such key details seemed “quite an accomplishment for a prisoner serving in a support role,” notes historian Jim Woodrick.
Woodrick confirms that a soldier by the name of Leroy Carter had, indeed, served with the 3rd Iowa.
However, a July 18, 1863, report from Confederate scout Sam Henderson offers a strangely complementary tale.
On July 15, two scouts under Henderson’s command were waylaid by an ambush of “15 Yankees,” and while most of the Federal gunfire “fortunately missed,” one shot at least hit the horse of one of the scouts. “[T]hey overtook and captured him,” wrote Capt. Henderson, in charge of the scouts; “a very serious loss to my command—one of the best men I ever knew.”
The name of the scout: Leroy Carter.
“Whether just an amazing coincidence, or whether Carter was an incredibly observant prisoner, a trusted scout or a Union spy may never be known,” Woodrick has concluded. “The fact is, however, a man named Carter provided incredibly detailed and important information at just the right time to Sherman. . . .”
The foiled plan, lamented Johnston, allowed the ammunition train to safely reach Sherman, who later wrote that he used his artillery “pretty freely.”
“This made it certain the abandonment of Jackson could be deferred little longer,” he concluded—and by July 17, he and his forces had (again) abandoned the Mississippi capital.
“This seems to me a fit supplement to the reconquest of the Mississippi River itself,” Sherman later wrote. And it might all be attributed to the puzzling appearance of an Iowan by the name of Leroy Carter—if, indeed, that’s who he really was.
 Joseph E. Johnston, Narrative of Military Operations, Directed, During the Late War Between the States, by Joseph E. Johnston, General, C.S.A. (New York: D. Appleton & Co., 1874), 206.
 Sherman, report, O.R. XXVI, Pt. 2, 535.
 Johnston, 208.
 Parke to Sherman, 15 July 1863, O.R. XXVI, Pt. 2, 554-555.
 Jim Woodrick, The Civil War Siege of Jackson, Mississippi (Charleston, S.C.: History Press, 2016), 83. I want to give a shout-out to this great little book, which is packed with excellent details about the entire siege. The action was a coda to the Vicksburg Campaign, but it’s often overlooked. Jim’s book does the story real justice.
 Woodrick, 82-83.
 Henderson to Johnston, 18 July 1863, O.R. XXVI, Pt. 3, 1015.
 Woodrick, 83.
 William T. Sherman, Memoirs of General William T. Sherman (New York: D. Appleton & Co., 1875), 331.
 Johnston first abandoned Jackson on May 14, 1863, just hours after arriving in the city from Tennessee.
 Sherman, report, 537.