Final answer:
The author of the letter from the "Soldier 20th US Colored Infantry to Abraham Lincoln in 1864" hoped for a Union victory that would also advance freedom and equality for African Americans, resulting from the impact of the Emancipation Proclamation and the inclusion of nearly 200,000 black soldiers in the Union Army.
Step-by-step explanation:
The author of the letter from the "Soldier 20th US Colored Infantry to Abraham Lincoln in 1864" hoped that the result of the Civil War would be not just a Union victory but a meaningful change in the United States. He aspired that the enormous sacrifices made during the war and the active participation of almost 200,000 black soldiers would not only lead to the preservation of the Union but also secure freedom and equality for African Americans.
Through the Emancipation Proclamation and the inclusion of Black troops in the Union forces, a new birth of freedom was envisioned by President Lincoln, with the hope that it would eradicate the scourge of slavery and lead to a new bi-racial democracy post-war.
The Emancipation Proclamation set the stage for these hopes by changing the course of the war and strengthening the Union with additional manpower. Moreover, it aimed to weaken the Confederacy by stripping away their slave labor, which would in turn severely cripple their ability to sustain the war effort. Also significant was the expectation that, through their service, African Americans would assert their right to citizenship, and the just-ended conflict would open doors to legal marriage, family reunions, and employment opportunities, while confronting and working against the persisting racial injustices.