Why was military district in need to control the southern states before they were readmitted into the union?

The military district was established to enforce federal authority and ensure compliance with Reconstruction policies following the Civil War. Southern states had to be controlled to protect the rights of newly freed African Americans and to prevent the resurgence of Confederate sympathies. Federal troops were deployed to maintain order, oversee elections, and ensure that states adopted new constitutions that guaranteed civil rights. This military oversight was deemed necessary to facilitate a smooth reintegration of the southern states into the Union.