Abraham Lincoln believed reconstruction of the South, after the Civil War was over, needed to be lenient to heal the country. He felt to be harsh would cause more problems than it cured. But the majority of Congress disagreed.
After the Civil War was over, Congress passed the Reconstruction Act of 1867. President Andrew Johnson, who had taken over as President of the United States after Lincoln was assassinated, vetoed this bill, but Johnson's veto was overruled by Congress.
The Reconstruction Act of 1867 placed Southern governments under military rule. The South was divided into five military districts, each run by a general in the U.S. Army. The five districts were (1) Virginia; (2) North and South Carolina; (3) Georgia, Alabama, and Florida; (4) Mississippi and Arkansas; and (5) Texas and Louisiana. Tennessee was the only prior Confederate state that was not placed under military rule because Tennessee had many Union supporters during the war. Around 200,000 troops were placed in the South to enforce military rule.
Thousands of government officials were removed from office in the South and replaced with military commanders. Different commanders ruled in different ways. Some were very good at their jobs, and some were not. They had very few restrictions. They could be cruel or unfair and get away with it. It was a very harsh time for the population in the South.
One thing all military commanders did because they were told to do so by Congress was to place former slaves in positions in government. These former slaves knew nothing about government or money. They were not trained for their jobs. Nearly all were puppets under the control of army officials.
Military rule in the South lasted for 10 years, until 1877, when the Republican party agreed to return Southern states to home rule in exchange for their support of the Republican candidate for president, Rutherford B. Hayes. That was the end of reconstruction.