After the end of the American Civil War, as part of the ongoing process of Reconstruction, the United States Congress passed four statutes known as Reconstruction Acts. (March 2, 1867, 14 Stat. 428-430, c.153; March 23, 1867, 15 Stat. 2-5, c.6; July 19, 1867, 15 Stat. 14-16, c.30; and March 11, 1868, 15 Stat. 41, c.25) The actual title of the initial legislation was "An act to provide for the more efficient government of the Rebel States" and it was passed on March 2, 1867. Fulfillment of the requirements of the Acts was necessary for the former Confederate States to be re-admitted to the Union. The Acts excluded Tennessee, which had already ratified the 14th Amendment and had been readmitted to the Union.
A key feature of the Acts included the creation of five military districts in the South, each commanded by a general, which would serve as the acting government for the region. National Archives, War Department Records, Second Military District 3/11/1867 - 7/28/1868, Administrative History Note:
The establishment of military government in the Southern states as a feature of the system imposed under the Reconstruction Acts was due primarily to the fact that the introduction of Negro suffrage was thought to be possible only through a show of strength. In May and June of 1865 President Andrew Johnson had appointed Provisional Governors for the Southern states and had ordered the enforcement of Federal laws in those states. These measures were intended to have the result, when a state's constitution should have been amended, of restoring the state "to its constitutional relations to the Federal Government," but Congress, by an act of March 2, 1867 (14 Stat. 428), divided the ten Southern states into five military districts, each to be commanded by an officer not below the rank of brigadier general. Under the act the primary duties of these commanders were "to protect all persons in their rights of person and property, to suppress insurrection, disorder, and violence, and to punish, or cause to be punished, all disturbers of the public peace and criminals." Their duties in the reorganization of the state governments, as set forth in an act of March 23, 1867 (15 Stat. 2), were extended to include the registration of qualified voters who had taken the oath of allegiance to the United States, the supervision of the election of delegates to state constitutional conventions, and the transmittal to the President of certified copies of the constitutions adopted. The War Department, in conformity with the act of March 2, issued AGO General Order 10, March 12, 1867. which assigned commanders and announced locations of the several headquarters. The powers of these commanders were both civil and military; and the civil powers exercised were usually referred to as "military government." So far as their military duties were concerned, district commanders were subordinate to the General of the Army and the Secretary of War just as were department commanders. In their civil capacity, however, district commanders were entirely independent of the War Department except in matters of removal, appointment, and detail. An act of July 19, 1867 (12 Stat. 14) defined the powers of the district commander to suspend or remove from office persons occupying positions in the civil government of the state concerned; the provisional governments established by the President were thus made subject to the military commanders. A joint resolution of February 18, 1869 (15 Stat. 344), provided for the removal from office of persons holding civil offices in the "provisional governments" of Virginia, Texas, and Mississippi who could not take the oath of allegiance and directed the district commanders to fill the resulting vacancies by the appointment of persons who could take the oath. Major General Daniel E. Sickles assumed command of the Second Military District on March 21, 1867. The military subdistricts of North and South Carolina were discontinued in April 1867, and the territory embraced in the command was divided into posts. This organization was found to facilitate the transaction of business and the prompt administration of justice. Post commanders were immediately responsible for seeing that people within their jurisdiction obeyed all existing laws and orders. To bring about more efficient administration of justice and to give greater security to life and property, the sheriffs and other officers of municipal organizations with the District were put under the immediate control of a military officer--the provost marshal general. Sheriffs, chiefs of police, city marshals, chiefs of detectives, and town marshals in North and South Carolina were ordered to report to him.