What is the purpose of the scene consisting of Lincoln speaking with the black and white soldiers?

The scene featuring Lincoln speaking with both Black and white soldiers serves to highlight themes of unity and equality during a pivotal moment in American history. It underscores Lincoln's commitment to the principle of emancipation and the fight against slavery, illustrating his vision for a nation where all individuals, regardless of race, can contribute to the common cause. This interaction also emphasizes the shared sacrifice of soldiers from different backgrounds, reinforcing the idea that the struggle for freedom and justice is a collective endeavor.