Which event directly followed the end of the Civil War affecting the rights of African Americans?

The enactment of the Black Codes directly followed the end of the Civil War and had a profound impact on the rights of African Americans. After the Union's victory in 1865, Southern states were quick to implement these laws aimed at regulating the labor and behavior of formerly enslaved individuals. The Black Codes restricted African Americans' rights by enforcing segregation, limiting their ability to own property, and controlling their labor, thereby attempting to maintain white supremacy and the social order that had existed before the war. These laws were designed to circumvent the progress made during the Reconstruction period, setting the stage for systemic discrimination that continued for decades.

The other events mentioned also significantly impacted African Americans but occurred during a broader timeline of Reconstruction. The Freedmen's Bureau was established to assist newly freed slaves, providing education and support but was not a direct consequence of the Civil War's conclusion. The passing of the 15th Amendment, which granted African American men the right to vote, came a bit later in 1870, while Jim Crow laws were instituted after the Black Codes, further codifying racial segregation in the South. Thus, the Black Codes represent the immediate and oppressive response to the shifting dynamics of power after the Civil War.