When President Abraham Lincoln announced the impending passage of the Emancipation Proclamation in early 1863, the stakes of the Civil War shifted dramatically. A Union victory would mean no less than revolution in the South, where the “peculiar institution” of slavery had dominated economic, political and social life in the antebellum years.

In April 1865, as the war drew to a close, Lincoln shocked many by proposing limited suffrage for African Americans in the South. He was assassinated days later, however, and his successor Andrew Johnson would be the one to preside over the beginning of Reconstruction.

Johnson, a former senator from Tennessee who had remained loyal to the Union during the war, was a firm supporter of states’ rights and believed the federal government had no say in issues such as voting requirements at the state level.

Under his Reconstruction policies, which began in May 1865, the former Confederate states were required to uphold the abolition of slavery (made official by the 13th Amendment to the U.S. Constitution), swear loyalty to the Union and pay off their war debt. Beyond those limitations, the states and their ruling class—traditionally dominated by white planters—were given a relatively free hand in rebuilding their own governments.

Even as former enslaved people fought to assert their independence and gain economic autonomy during the earliest years of Reconstruction, white landowners acted to control the labor force through a system similar to the one that had existed during slavery.

To that end, in late 1865, Mississippi and South Carolina enacted the first black codes. Mississippi’s law required Black people to have written evidence of employment for the coming year each January; if they left before the end of the contract, they would be forced to forfeit earlier wages and were subject to arrest.

In South Carolina, a law prohibited Black people from holding any occupation other than farmer or servant unless they paid an annual tax of $10 to $100. This provision hit free Black people already living in Charleston and former slave artisans especially hard. In both states, Black people were given heavy penalties for vagrancy, including forced plantation labor in some cases.

Under Johnson’s Reconstruction policies, nearly all the southern states would enact their own black codes in 1865 and 1866. While the codes granted certain freedoms to African Americans—including the right to buy and own property, marry, make contracts and testify in court (only in cases involving people of their own race)—their primary purpose was to restrict Black peoples’ labor and activity.

Some states limited the type of property that Black people could own, while virtually all the former Confederate states passed strict vagrancy and labor contract laws, as well as so-called “anti-enticement” measures designed to punish anyone who offered higher wages to a Black laborer already under contract.

Black people who broke labor contracts were subject to arrest, beating and forced labor, and apprenticeship laws forced many minors (either orphans or those whose parents were deemed unable to support them by a judge) into unpaid labor for white planters.

Passed by a political system in which Black people effectively had no voice, the black codes were enforced by all-white police and state militia forces—often made up of Confederate veterans of the Civil War—across the South.

The restrictive nature of the codes and widespread Black resistance to their enforcement enraged many in the North, who argued that the codes violated the fundamental principles of free labor ideology.

After passing the Civil Rights Act (over Johnson’s veto), Republicans in Congress effectively took control of Reconstruction. The Reconstruction Act of 1867 required southern states to ratify the 14th Amendment—which granted “equal protection” of the Constitution to former enslaved people—and enact universal male suffrage before they could rejoin the Union.

The 15th Amendment, adopted in 1870, guaranteed that a citizen’s right to vote would not be denied “on account of race, color, or previous condition of servitude.” During this period of Radical Reconstruction (1867-1877), Black men won election to southern state governments and even to the U.S. Congress.

As indicated by the passage of the black codes, however, white southerners showed a steadfast commitment to ensuring their supremacy and the survival of plantation agriculture in the postwar years. Support for Reconstruction policies waned after the early 1870s, undermined by the violence of white supremacist organizations such as the Ku Klux Klan.

By 1877, when the last federal soldiers left the South and Reconstruction drew to a close, Black people had seen little improvement in their economic and social status, and the vigorous efforts of white supremacist forces throughout the region had undone the political gains they had made. Discrimination would continue in America with the rise of Jim Crow laws, but would inspire the civil rights movement to come.