Final answer:
African Americans joined the army as a way to demonstrate bravery and patriotism, to symbolically fight against slavery and for equality, and to use their military service as a platform to push for social and civil rights change despite facing severe discrimination.
Step-by-step explanation:
African Americans wanted to join the army despite unjust treatment for multiple reasons. They sought to prove their bravery and honor in instances such as World War I and World War II, where they served with distinction in segregated units. African American soldiers viewed military service not just as a fight for the United States, but also as a symbolic fight against slavery and for equality. Serving in the army provided them with a platform to demonstrate patriotism and an opportunity to demand respect and social change. Despite facing severe discrimination and barriers such as economic hardship, they enlisted and often used their experiences to push for progress in civil rights upon their return. The courage and valor of regiments like the Fifty-Fourth Massachusetts, as well as the activism of soldiers like Charles Young and James Henry Gooding, were critical in challenging the nation's racial hierarchy both during and after their service.