After the Civil War (April 1865), it was necessary to rebuild the Union, devastated by the hard campaigns of Grant and Sherman, covered with ruins, hatreds and resentments. American historians call the Reconstruction Period the years from 1865 to 1877, the date when the federal armies evacuated the South, ending the state of emergency that followed the defeat of the slavers.
After the assassination of Lincoln, President Andrew Johnson, a man of the South of "poor white" origin, who had become vice president, despite his modest birth, for his loyalty to the Union, was proclaimed president. Rude, stubborn, showed signs of balance and good sense, following the policy decided by Lincoln.
President Johnson vetoed the laws that seemed dire, attracting the wrath of the radicals, who accused him before the Senate, constituted in Supreme Court, but Johnson was acquitted (1868). Lost by the president all possibility of re-election, the candidate of the radicals, the illustrious General Grant, one of the victors of the civil war, was elected eighteenth President of the United States in 1868; then he would be re-elected for a second term.
The South was profoundly transformed with the end of slavery and with the Reconstruction. Ruined by the war and unable to pay the slaves turned into free laborers, the planters had to parcel out their large estates, dividing them into small lots.
Once the slavery disappeared, the black problem continued; despite legislative efforts, the whites denied equality to the four million blacks (at the end of the century, it would be 10 million). When the state of emergency was lifted and the last federal troops left in 1877, the governments and the legislatures of the South found the means of separating blacks from political life.
The "grandfather clause" (the right to vote was reserved for those whose ancestors had voted in 1860) and the electoral tests (to read, write, correctly interpret an article of the Constitution), deprived the black majority of the electoral card .
Segregation was systematically applied in schools, transportation, churches, restaurants, etc. It even resorted to terror, to lynching, to summary executions of blacks. Secret societies like the Ku-Klux-Klan, whose members wore hoods and terrorized blacks, made the theoretical equality of civil rights illusory, and the North closed its eyes.