How did allowing free blacks to fight in the war help the union?

Allowing free blacks to fight in the Civil War significantly bolstered the Union's manpower, providing much-needed soldiers to combat the Confederacy. Their participation not only increased troop numbers but also served as a powerful symbol of the fight for freedom and equality, helping to galvanize support for the Union cause. Additionally, it undermined the Confederacy's social structure by challenging the institution of slavery and demonstrating the capabilities and commitment of African Americans to the fight for their own liberation. Overall, their involvement contributed to the Union's strategic advantage and moral standing in the war.