Lieber Code of 1863: Section VI
SECTION VI.–Exchange of prisoners–Flags of truce–Flags of protection.
105. Exchanges of prisoners take place–number for number–rank for rank–wounded for wounded–with added condition for added condition–such, for instance, as not to serve for a certain period.
106. In exchanging prisoners of war, such numbers of persons of inferior rank may be substituted as an equivalent for one of superior rank as may be agreed upon by cartel, which requires the sanction of the Government, or of the commander of the army in the field.
107. A prisoner of war is in honor bound truly to state to the captor his rank; and he is not to assume a lower rank than belongs to him, in order to cause a more advantageous exchange, nor a higher rank, for the purpose of obtaining better treatment.
Offenses to the contrary have been justly punished by the commanders of released prisoners, and may be good cause for refusing to release such prisoners.
108. The surplus number of prisoners of war remaining after an exchange has taken place is sometimes released either for the payment of a stipulated sum of money, or, in urgent cases, of provision, clothing, or other necessaries.
Such arrangement, however, requires the sanction of the highest authority.
109. The exchange of prisoners of war is an act of convenience to both belligerents. If no general cartel has been concluded, it cannot be demanded by either of them. No belligerent is obliged to exchange prisoners of war.
A cartel is voidable as soon as either party has violated it.
110. No exchange of prisoners shall be made except after complete capture, and after an accurate account of them, and a list of the captured officers, has been taken.
111. The bearer of a flag of truce cannot insist upon being admitted. He must always be admitted with great caution. Unnecessary frequency is carefully to be avoided.
112. If the bearer of a flag of truce offer himself during an engagement, he can be admitted as a very rare exception only. It is no breach of good faith to retain such flag of truce, if admitted during the engagement. Firing is not required to cease on the appearance of a flag of truce in battle.
113. If the bearer of a flag of truce, presenting himself during an engagement, is killed or wounded, it furnishes no ground of complaint whatever.
114. If it be discovered, and fairly proved, that a flag of truce has been abused for surreptitiously obtaining military knowledge, the bearer of the flag thus abusing his sacred character is deemed a spy.
So sacred is the character of a flag of truce, and so necessary is its sacredness, that while its abuse is an especially heinous offense, great caution is requisite, on the other hand, in convicting the bearer of a flag of truce as a spy.
115. It is customary to designate by certain flags (usually yellow) the hospitals in places which are shelled, so that the besieging enemy may avoid firing on them. The same has been done in battles when hospitals are situated within the field of the engagement.
116. Honorable belligerents often request that the hospitals within the territory of the enemy may be designated, so that they may be spared.
An honorable belligerent allows himself to be guided by flags or signals of protection as much as the contingencies and the necessities of the fight will permit.
117. It is justly considered an act of bad faith, of infamy or fiendishness, to deceive the enemy by flags of protection. Such act of bad faith may be good cause for refusing to respect such flags.
118. The besieging belligerent has sometimes requested the besieged to designate the buildings containing collections of works of art, scientific museums, astronomical observatories, or precious libraries, so that their destruction may be avoided as much as possible.