Final answer:
The Union won the American Civil War, which resulted in significant government and social changes, including the abolition of slavery.
Step-by-step explanation:
The American Civil War, which lasted from 1861 to 1865, was a conflict between the northern states (Union forces) and the southern states (Confederate forces), primarily over the issue of slavery. The Union emerged victorious in the conflict, leading to significant changes in the national government and society. Following the Union's victory, the United States preserved its integrity and abolished slavery. The Confederacy, on the other hand, was left in ruins with its economy devastated and its governmental structures dismantled.
Post-war, the period known as Reconstruction aimed to reintegrate the southern states into the Union, protect the rights of newly freed slaves, and rebuild the South's infrastructure. However, this period also witnessed the rise of segregation laws, known as Jim Crow laws, and the emergence of racially motivated violence, notably by the Ku Klux Klan. The reconstruction era saw a power shift toward the national government, reinforced by significant constitutional amendments, including the Fourteenth and Fifteenth Amendments, which granted citizenship and voting rights to African Americans.
The war and its aftermath were transformative, reshaping the United States in terms of civil rights, governmental authority, and the very fabric of American society. Unfortunately, despite the legal gains for African Americans during Reconstruction, the era failed to dismantle the social and economic structures that perpetuated racial inequality and white supremacy in the South.