Final answer:
Between 1857 and 1877, the federal government's redefinition of African American standing in society was influenced by constitutional amendments, federal legislation combating racial violence, and the persistent advocacy of civil rights leaders amidst a backdrop of enduring white supremacy.
Step-by-step explanation:
The events and movements that prompted the federal government to redefine the standing of African Americans in American society between 1857 and 1877 include the passage of constitutional amendments and federal legislation as well as grassroots activism and the immense pressure of the ongoing racial violence in the South.
Significant constitutional amendments during the era, specifically the Thirteenth, Fourteenth, and Fifteenth Amendments, were enacted to abolish slavery, ensure equal protection under the law, and protect the right to vote, respectively. The Enforcement Acts between 1870 and 1871 made it criminal to deprive African Americans of their civil rights in response to the violent behavior of groups like the Ku Klux Klan. However, the commitment to these changes waned as the federal government's attention shifted towards other issues, and violence against African Americans persisted.
The Civil Rights Act of 1875 was an effort by Congress to prevent racial discrimination in all public venues, although it was not supported by southern states and would eventually be declared unconstitutional. Frederick Douglass, Sojourner Truth, and others advocated for the rights of African Americans and other minorities during this period. Despite the hope these measures initially generated, by 1876, with the reestablishment of 'home rule' by southern Democrats, African Americans found themselves trapped once again in a world dominated by white supremacy that restricted their rights. This leads to many African Americans migrating to the North, though they faced de facto discrimination there as well.