He cannot be subjected to conscription, or forced military service, save by the written orders of the highest military authority of the department, under such regulations as the President or Congress may prescribe. Domestic servants, blacksmiths, carpenters, and other mechanics, will be free to select their own work and residence, but the young and able-bodied negroes must be encouraged to enlist as soldiers in the service of the United States, to contribute their share toward maintaining their own freedom, and securing their rights as citizens of the United States.
1860s, 1865, Special Field Order No. 15 (January 1865)