On the recordJuly 29, 1863
It is therefore ordered, That for every soldier of the United States killed in violation of the laws of war a rebel soldier shall be executed, and for every one enslaved by the enemy or sold into slavery a rebel soldier shall be placed at hard labor on the public works and continued at such labor until the other shall be released and receive the treatment due to a prisoner of war.
Source
presidency.ucsb.edu




