I think this statement is incredibly telling about the importance of slaves in this era. He is saying that, unfortunately, the amount of black soldiers is limited because if they are enlisted, they leave behind their "first priority" of the white man they serve at home. It is wild to me how slavery is so normalized that they would rather prioritize it than prioritize the impending doom of war.

The idea that freed slaves could carry a fighting spirit toward their opponents could be a blessing or a curse. On one hand, this could mean that the soldiers would be incredibly effective in their work of hunting and killing their opponents, but on the other hand, they could, in some cases, "fly off the handle" and kill masses of people who may have done them wrong that they were not assigned.

This portion of General Sherman's response shows the position that Sherman has on slavery, which overall can impact the fate of the slaves, their owners, and the overall outcome of the future of the freedmen.