The men in the camp of the 10th Illinois Cavalry were in an uproar. Pvt. John O’Brien was being held in the nearby camp of the 1st Mississippi Infantry, African Descent, (a Union unit despite its name). Col. Isaac F. Shepard, the commander of the 1st Mississippi,  had ordered O’Brien to be flogged by some of the black soldiers of Shepard’s regiment.

On May 30, 1863, O’Brien, from the all-white 10th Illinois Cavalry, had gotten drunk and gone on an abusive rampage. He and an unnamed friend (who had managed to escape Shepard’s retribution) had come into the 1st’s camp and violently kicked Private Henry Lee so brutally in the crotch that he would be incapacitated for several days. The two Illinoisans then went to a nearby slave cabin, where they attempted to rape a 10-year-old girl, threatening the girl’s mother with a hatchet and throwing the child’s grandmother violently against the fireplace, kicking her when she fell. They continued their assault on two other individuals in the same room.

When Col. Shepard found out what was going on, he quickly had O’Brien apprehended, and ordered some of his African American soldiers to whip him. Shepard, an abolitionist, grieved at the outrages committed by white Union soldiers against the freedpeople. He felt compelled to take stern action – as no one else in the army seemed to care.

When Capt. Christopher Anderson and Lt. Thomas Vredenburgh entered Shepard’s headquarters, they were enraged at the idea that one of their soldiers had been whipped by black men. They were nearly uncontrollable in their wrath, and warned Shepard that they could not be held responsible for any actions their men might take. They demanded that Shepard resign immediately for having “disgraced the service” and that he come to the 10th Cavalry’s camp and tender a formal apology.

Shepard was having none of it. He would testify in a Court of Inquiry a few days later that he felt compelled to take action, for so many crimes had gone unpunished. After much detailed testimony, cataloging a number of atrocities committed by white Union soldiers upon black men, women, and children, Shepard was exonerated. However, in the meantime, while the investigation was taking place, he was temporarily removed from command.

On June 7, therefore, Col. Hermann Lieb would command the African Brigade – not Shepard. And on that day, the Rebels would attack.

Source: Milliken’s Bend: A Civil War Battle in History and Memory, pp. 76-78.