Reconstruction is the name given to the process of "reconstructing" the South. This meant determining how, under what conditions, and with what significant changes the South could reenter the Union. This process was hotly contested, involving both a contest over federal authority and a redefinition of basic rights for African-Americans in the South.
Reconstruction really began as early as 1864, when President Lincoln proposed a plan by which former Confederate states could be readmitted into the Union if ten percent of voters eligible in the 1860 election swore loyalty to the United States government. This so-called "Ten Percent" plan was countered by a more punitive plan known as the Wade-Davis Bill that, while pocket vetoed by Lincoln, marked the battle lines for Reconstruction by making basic rights for African-Americans a condition for readmission. Lincoln himself moved toward this position before his death, seeming to advocate suffrage for African-American veterans in the Union Army.
After Lincoln's assassination, President Andrew Johnson had little interest in protecting the rights of freedmen. He extended amnesty to most Confederates, including their leaders, and vetoed legislation passed by Congress, including an extension of the Freedmen's Bureau and the Civil Rights Act of 1866, that extended basic rights to African-Americans. "Radical" Republicans in Congress impeached Johnson for violating the Tenure of Office Act, and afterwards seized control of what became known as "Congressional" Reconstruction. In 1867, they divided the South into military occupation districts, using federal troops in some areas to force compliance, and mandating that Southern states ratify the Thirteenth and Fourteenth Amendments.
On the local level, African-Americans made considerable strides in politics, getting individuals elected to local and state offices as well as to Congress. Many schools were built, and local organizations sustained black civic and political life. But without owning land, most remained locked in poverty, working as sharecroppers and tenant farmers who could barely make enough to meet the considerable debts they piled up. They also faced violent retribution from the Ku Klux Klan and other terrorist groups that emerged during Reconstruction to try to preserve white supremacy.
By the 1870s, Radicals began to lose control of Congress, and Southern Democrats, through a mixture of violence, fraud, race-baiting, and compromise, regained control of Southern state governments. By the time the Compromise of 1877 ended federal occupation of the last handful of Southern states, Reconstruction was already ended in most of the South. Its end paved the way for the establishment of Jim Crow governments, founded on the principle of white supremacy, that would endure until the 1960s. While black political activism was a lasting legacy of Reconstruction, so was violence, poverty, and discrimination.