From Kelly Mezurek:
Burnside informed Ferrero that the 4th Division would lead the charge, with the 43rd USCT in front, and that he should begin immediately to prepare the men. Burnside chose the black troops because he believed that they were the most rested of his army. He thought that his white troops were too drained by their losses from battle, picket duty, and illness. Of course, the African American soldiers were just as worn down, and, more significantly, they had less experienced officers, making Burnside’s reasoning questionable. He defended such criticisms by arguing that the blacks would only enter first and that tested white troops would actually perform the most important task of capturing Petersburg after the USCT had secured Cemetery Hill. Burnside instructed Ferrero to inform Siegfried and Col. Henry G. Thomas, commander of the 2nd Brigade of the 4th Division, of the upcoming event. In preparation for the attack, Ferrero wrote to the assistant adjutant general that Lieutenant Colonel Blackman was needed, as “no field officer of the regiment is
with it,” and that “an officer has to be detailed from another regiment to perform his duties.” On July 14, the War Department sent word to the superintendent of volunteer recruiting services in Ohio that the secretary of war had requested that Governor Brough release Blackman from recruiting duty and send him to the front with any new enlistees that he could bring.50
On July 17 an impatient Ferrero sent word to the IX Army Corps headquarters that his men, who were supposed to help lead the assault, needed time to rest and prepare for their important role. He explained to his superiors that the 4th Division had been performing an enormous amount of fatigue duty, often at night. Not only were the men exhausted, but the non-ending toil had left him little time to train them. The complaint was not an attempt to get out of the upcoming battle; it was a plea to participate. Ferrero firmly reminded Burnside of the leader’s promise to finally engage the entire division of black troops in a planned military action. Yet the only training Ferrero could fit in during the demanding construction schedule was to pull out one regiment a day to drill in the two weeks before the planned assault—although Lt. Robert Beecham of the 23rd USCT remembered only three to four hours of instruction. Capt. Albert Rogall made four references to 27th’s “preparations for a big fight” in his journal during the weeks before the explosion at the Battle of the Crater, but the military inexperience of the blacks became painfully clear when they practiced with their weapons. One surgeon reported that in a single day he had to perform seven thumb operations after the training began.
Mezurek, Kelly D.. For Their Own Cause: The 27th United States Colored Troops (Civil War in the North) (Kindle Locations 2399-2419). Kent State University Press. Kindle Edition.