The narrator of the documentary says that the formation of the 54th Massachusetts had a "devastating psychological impact" on the confederacy. Explain the reasons why this is so

The formation of the 54th Massachusetts Regiment was made up of African American soldiers, being one of the first formations of the Union Army to be made up exclusively of black people. Many of them were free men, but others were freed slaves fighting for an end to slavery in the southern states of the country. Its creation occurred after the Emancipation Declaration, through which President Lincoln made the abolition of slavery one of the main objectives of the war, attracting many African-Americans to the cause of the Union.

For the Confederate soldiers, the fact that a regiment of people regarded by them as inferiors faced them in battle meant an affront to their convictions, but also created fear in the face of possible personal revenge, and even in the face of the possibility that their own slaves rebelled and joined this regiment.