This is a photograph taken by one of the Union Officers during the Civil War. Many children were orphaned or abandoned on plantations. The rich white planters removed their families and left the slaves behind. Then as now, the able bodied young and resourceful men and women fled. The young children, women and old people were left behind.
The laws in the USA forbade the selling of children under the age of 10, so from age 10 an enslaved child was fair game. Of course, this was only on the honor system, as if slave owners had any honor, what a joke. This poor kid looks between 10 to 13 years old. He is shoeless and dressed in filthy rags.
His face is the face of American slavery, not the fiction or the drawings. This is an actual photograph not some contrived image of the "happy darky," but the lost look of an orphaned child. He was either orphaned on the auction block or by the ravages of the war. Either way, he was an American slave orphan.