The Acting Secretary of War ( Wainwright ) to the Secretary of State

WPD 375–15

My Dear Mr. Secretary: In further reply to your letter of September 5, 1922, in which you request the views of the War Department on the questions to be taken up by the Commission of Jurists appointed by the United States and certain other countries to meet at The Hague on December 10, 1922, to consider amendment of the laws of war, I transmit herewith a draft, dated November 13, 1922, of rules to govern aircraft in war. These rules were formulated by duly appointed Army representatives, after careful study and conference with officials of your Department and of the Navy Department; they meet with my approval and, as an expression of War Department opinion, are intended to supersede the draft of similar rules transmitted to you with my letter of November 29, 1921, (WPD 165–4).47

Sincerely yours,

J. M. Wainwright
[Page 52]

Rules of Warfare for Aircraft as Proposed by the War Department

I. Definition, Nationality, Marking

An aircraft is a vehicle designed for or capable of the aerial transportation of persons or material. An aircraft permanently assigned to a vessel of war and usually accompanying the vessel may be regarded as a part of the vessel as long as it remains in physical contact therewith.
Aircraft may be public aircraft, belonging to or under the control of the state or its officers; or private aircraft, belonging to and under the control of private persons.
No aircraft may possess more than one nationality. Every aircraft shall bear marks, visible from all sides and so affixed as not to be capable of being altered while in flight through the air; which marks shall indicate (1) the nationality of the aircraft, and (2) her public or private character. Private aircraft shall be registered under national registration laws and shall bear internal or other identification marks conformable with her registration and also the name and residence of her owner.
The personnel of public aircraft shall carry with them uniforms and proper papers to show that they are in the public service. Unless under compelling necessity, they shall not leave the aircraft except in uniform.
The use of false external marks of nationality or character is forbidden. If, by any means thereof, a public belligerent aircraft simulates a private aircraft or a belligerent aircraft simulates a neutral aircraft, the aircraft and her personnel are outside the protection of the law.

II. Aerial Jurisdiction

A state has complete and exclusive jurisdiction in the air space above its territory and above its jurisdictional waters: provided, however, that nothing herein contained shall be deemed to exclude the application of the civil or criminal laws of the country of nationality of an aircraft to the fixing of the rights or liabilites consequent upon such acts done by, or such occurrences affecting persons on board said aircraft while in flight as do not affect persons or things external to said aircraft.
In time of war, any state, neutral or belligerent, may forbid the entrance, or regulate the entrance, movement, or sojourn of aircraft within its jurisdiction.
Within the immediate vicinity of naval or military operations, but outside of neutral jurisdiction, a belligerent commanding officer may forbid the passage of aircraft of any kind or prescribe the conditions of entrance.
The liability of an aircraft for violations of the laws of war is contingent upon her actual or constructive knowledge of the existence of the war.

III. Neutral Powers and Duties

A neutral government is obligated to intern such aircraft of belligerent nationality alighting within its jurisdicton (1) as are armed, equipped, or supplied so as to be capable of committing hostile acts, or (2) as are manned by members of the combatant forces of a belligerent.
Belligerent aircraft are bound to respect the rights of neutral powers and to abstain within neutral jurisdiction from all acts which, if knowingly permitted by a neutral power, would constitute a nonfulfilment of its neutrality.
A neutral government may intern any aircraft of belligerent nationality not conforming to its regulations.
The action of a neutral power in using the means at its disposal to prevent the violation of its neutrality by aircraft or to enforce its regulations concerning aircraft is not to be regarded as hostile.
A neutral government is bound to use the means at its disposal (1) to prevent the departure from its territorial jurisdiction of any aircraft of belligerent nationality in condition to make a hostile attack or carrying parts or materials which, when utilized, would make her fit for hostile attack; (2) to prevent the departure of any aircraft manned by members of the combatant forces of a belligerent; and (3) to prevent work upon any aircraft designed to prepare her to depart in contravention of the purpose of this paragraph.

IV. Neutral Aircraft

A neutral, public aircraft within belligerent jurisdiction or in the neighborhood of belligerent operations must respect belligerent instructions.
A neutral, private aircraft, found in a belligerent’s territorial jurisdiction or in the immediate vicinity of its military operations, must obey any order given it by the belligerent. Failure to obey justifies the use of necessary force. A neutral, private aircraft which, contrary to prohibitions, enters a belligerent’s territorial jurisdiction or the area of a belligerent’s actual military operations, is liable to confiscation and its personnel to treatment as prisoners of war, unless its entrance was made in ignorance of the prohibitions.
Neutral, private aircraft found by a belligerent in the territorial jurisdiction of the enemy may be requisitioned.
Bona fide and unconditional transfers of title to a neutral of public or private aircraft of a belligerent shall be respected by the opposing belligerent in each of the following cases, to wit:
in case a title, valid under the municipal law of the state of which the purchaser is a national, was acquired by such neutral either before the rupture of diplomatic relations between the belligerents concerned or more than 30 days before the outbreak of hostilities between them; and
in case the neutral purchaser of an aircraft, not subject to internment in the purchaser’s country, takes actual possession therein of such aircraft and, according to the laws thereof, the title so acquired is absolute.

V. Belligerent Aircraft

Enemy public aircraft are, on and after the outbreak of war, liable to seizure and confiscation, except as provided in paragraph 21 hereof.
Enemy, private aircraft found within the jurisdiction of a belligerent on the outbreak of war are exempt from confiscation. They are not entitled to days of grace, but may be sequestered or requisitioned.
Public aircraft, exclusively used in assisting the wounded and the sick are exempt from attack or capture and their pilots, medical personnel and the wounded and sick on board are inviolable, provided the following conditions are satisfied:
Aircraft privileged hereunder and their personnel shall conform, in respect of arming and of weapons and substances carried, with the requirements for private aircraft, as specified in paragraph 22 hereof.
Aircraft privileged hereunder shall not fly at an altitude greater than 3000 feet above the ground, nor shall they approach within 10 miles of the military lines of the enemy’s ground forces.
Aeroplanes and heavier-than-air craft privileged hereunder shall be painted white and marked on fuselage, on upper and lower surfaces of wings and on tail surfaces with a red cross, such as is mentioned in Art. 18 of the 1906 Geneva Convention; and lighter-than-air craft shall display, so as to be visible from above, from below, and from each direction of approach, a like red cross upon a white ground painted or otherwise indelibly marked upon their structure, such marks to be of such size and location as will admit of their being seen from great distances. The pilots and medical personnel of aircraft privileged hereunder shall wear brassards such as those specified in Art. 20 thereof.
Heavier-than-air craft privileged hereunder shall be of such type or types of construction as will distinguish them from the aircraft of war of the same belligerent. A photograph or sketch of the [Page 55] distinguishing silhouette of such heavier-than-air craft shall be sent to the opposing belligerent as soon as possible after the outbreak of hostilities and in any event before use of such privileged aircraft is made.
Private aircraft of belligerent or neutral nationality shall not be armed, but each of their personnel may be supplied with a sword or saber, a pistol and ammunition therefor. Except as aforesaid, a private aircraft shall not, in time of war, be so equipped or supplied as to be capable of committing a hostile act and, to that end, shall not carry arms, weapons, ammunition, projectiles, explosives, bombs, injurious liquids, or noxious gases heavier than air. Any belligerent aircraft so equipped or supplied and displaying the external marks of a private aircraft may be dealt with as an aircraft of war and her personnel are outside the protection of the law.
Private aircraft of belligerent nationality, flying either (1) over the territory possessed by the adversary nations, or (2) in sight thereof and outside the territory possessed by their own nation, or (3) in sight of the military operations, on land or on the high seas of the opposing belligerent, may, without warning, be dealt with as enemy aircraft of war, provided that neutral jurisdiction may, in no event, be violated.
Private aircraft of belligerent nationality flying over the territory possessed by their own nation must make the nearest available landing upon the approach of public aircraft of the opposing belligerent; else the former may be treated as aircraft of war.

VI. Personnel of Aircraft

The personnel of a captured, private, belligerent aircraft not guilty of violation of the laws of war, will be released, if they promise formally in writing not to undertake, while hostilities last, any service connected with the operations of the war. The personnel of a captured, public, belligerent aircraft are entitled to like treatment as that accorded to other members of the combatant forces of the enemy nation.
Upon capture of a neutral aircraft, such of her personnel as have not violated their duties as neutrals shall be released unconditionally.
Any member of the personnel of a belligerent or neutral aircraft is to be deemed a spy only if, acting clandestinely or on false pretenses, he obtains or seeks to obtain information in the zone of operations of a belligerent, with the intention of communicating it to the government or combatant forces of the enemy. The entire personnel of an aircraft displaying false marks in violation of the terms of paragraph 5 may also be treated as spies.
Acts of the personnel of correctly marked enemy aircraft, public or private, done or performed while in the air, are not to be deemed espionage.
If the sick or wounded members of the combatant forces of a belligerent are brought to a neutral country by an aircraft enjoying the privileges mentioned in paragraph 21 hereof, and are left therein, such persons upon the departure of the aircraft that brought them shall be interned.
If a public, belligerent aircraft alights in neutral territory in order to escape pursuit, its personnel shall be interned, together with the aircraft. In other cases of internment of the public or private aircraft of a belligerent nation, such of the members of its personnel as are not guilty of personal fault, in violating the laws or regulations of the interning state, shall be released if they promise in writing not to undertake, while hostilities last, any service connected with the operations of the war.

VII. Bombardment

Bombardment includes the dropping or discharging of a projectile or of any explosive or noxious substance. Bombardment by aircraft for the purpose of injuring noncombatants or of destroying or damaging private property not of a military character, as denned in paragraph 36 hereof, or of terrorizing the civilian population is forbidden.
Bombardment by aircraft of neutral and noncombatant vessels in enemy territorial waters or at sea is forbidden except under circumstances indicated by paragraphs 33 to 39 and by paragraphs 44 and 45 hereof or under circumstances under which attack upon such vessels by the surface warships of a belligerent is permitted.
Bombardment by aircraft of objects on enemy land areas and of vessels in the territorial waters in vicinity thereof is limited to bombardment (1) of combat areas, (2) of routes of communication leading thereto, and (3) of special military targets or objectives, and (4) to bombardment designed to enforce requisitions. The right of bombardment recognized in this paragraph is restricted by the following paragraphs hereof.
A combat area and the routes of communication leading thereto, within the meaning of the preceding paragraph, include (1) the land area within the actual range of such artillery of the bombarding belligerent as accompany its mobile land forces, (2) the territorial waters contiguous to said area and within the range aforesaid, and (3) the railways, highways, and reasonably expected routes of march or of advance of the combatant forces of the enemy to a distance of one hundred miles from the military lines of such enemy.
Bombardment of all objects within the areas mentioned in the preceding paragraph is permitted; except that neutral vessels, sacred edifices and buildings dedicated to religion or public worship, buildings used for artistic, scientific, or charitable purposes, and historic monuments, unless they are in use for the military purposes of the enemy, must be spared if identifiable; as must, also, military and other hospitals and hospital ships, used exclusively as such and places where the sick or wounded are collected. Such buildings, objects, and places may be indicated by marks visible to aircraft, the nature of which marks shall be notified to the opposing belligerent. The use of marks so notified to indicate other buildings, objects, or places than those specified above, is to be deemed an act of perfidy. The marks used as aforesaid shall be of uniform shape or design throughout the territory controlled by the notifying belligerent and shall be of two sorts, viz: (1) marks to indicate hospitals, hospital ships and places where the sick or wounded are collected and (2) marks to indicate other places and objects.
Outside the areas mentioned in paragraph 34, all bombardment by aircraft is forbidden except the bombardment of buildings or objects of the following nature, to wit: bodies of troops of the combatant forces of the enemy, military supply trains, and the vehicles composing the same, fortresses and military works, military or naval posts and establishments, warships, naval stations, dry docks, dock-yards, barracks, military encampments, military and naval warehouses and bases of supply, arsenals, depots of arms or war materiel, guns, weapons and ammunition and such implements, appliances and materials as are intended for, or peculiarly adapted to warfare, munitions plants, factories in use for making guns, rifles and the implements and materials peculiar to war, steel mills or factories, iron foundries, aqueducts, bridges, railway lines and railway stations, canals and their locks, gas works, electric light or power plants, halls or buildings in use by the legislature of the war-making government and office buildings used by the military or naval departments of such government.
In conducting a bombardment, the obligation of a belligerent is discharged if due care is exercised not to injure objects exempt from attack which happen to be in the vicinity of the permitted target. So far as practicable, the destruction of permitted targets shall not involve injury to persons or to things that are not essential parts or appurtenances of such targets. When canals or railway lines are bombarded, vessels, trains, and cars other than those which carry troops or objects that are themselves legitimate targets, shall, so far as practicable, be spared. No object shall be bombarded on mere suspicion or conjecture of its being a legitimate target. In case of the bombardment of an object other than a legitimate target, it shall [Page 58] be deemed a friendly and commendable act for a neutral government to inquire into the circumstances that may have afforded to the bombarding belligerent reasonable cause to believe that the objective of the bombardment was a legitimate target.
Bombardment to enforce payment of money contributions is forbidden. Requisition by an air force upon a town or place of materials and supplies of a military nature or capable of subserving the needs of a military force, not exceeding those which the requisitioning air force is able to use therein or presently to carry away therefrom in their aircraft, is permitted, if not out of proportion to the resources of the town or place. Failure to comply with a permitted requisition may be punished by bombardment.

VIII. Visit, Search and Capture of Private Craft

Outside of neutral jurisdiction, enemy, private craft, including surface and sub-surface vessels, as well as aircraft, are liable to capture by aircraft and otherwise and are liable to condemnation.
A neutral, private aircraft is liable to capture and condemnation:
if it resists a public, belligerent aircraft or flees the exercise of belligerent rights
if it carries contraband
if it is engaged in an enterprise in the course of which it has assisted the enemy or otherwise violated its duties as a neutral
if it is within a prohibited war area, after knowledge of the prohibition.
A neutral, private aircraft is liable to capture:
if its papers are lacking, insufficient or irregular
if it conceals or suppresses material documents or information asked for by a belligerent examining officer
if it is manifestly out of the area justified by its papers.
Outside of neutral jurisdiction, belligerent aircraft of war have the right to visit and search private craft, including surface and sub-surface vessels and aircraft. Visit and search by aircraft of war shall be conducted in the nearest practicable place to that in which the craft liable thereto were encountered. A belligerent aircraft of war may, by suitable signal seasonably notified by the belligerent government, require a private aircraft to follow and alight where indicated.
If the circumstances make visit and search by an aircraft of war impracticable, craft liable to visit and search may be ordered to proceed under escort as directed, in order to enable other examination to be made.
Refusal to submit to visit and search or to afford such means and facilities therefor as are available or comply with the proper direction of a belligerent aircraft of war justifies bombardment or other attack by the aircraft of war.
Enemy craft and such neutral craft as are found, upon visit and search, to be liable to capture and condemnation by reason of having assisted the enemy in violation of their duties of neutrality, may be destroyed in case taking them into port for adjudication would be impossible or would imperil the safety of the capturing aircraft or the success of the operations then being conducted by the latter; provided, nevertheless, that no craft shall be destroyed unless her personnel have first been placed in safety. Neutral craft found, after visit and search, to be liable on other grounds to capture or condemnation must either be taken into port or must be released; the destruction or injury of such craft being forbidden. Contraband cargo and enemy cargo on neutral craft may be destroyed in cases in which such craft are found, upon visit and search, to have been justly subject to seizure, but in which it is impossible or impracticable, on grounds specified above, to take such craft into port for adjudication.
Destruction of a neutral aircraft entitles the owner of such aircraft and of the property on board to compensation, even when such aircraft is justly subject to condemnation, unless destruction is authorized by the preceding paragraph hereof.
In the event of the condemnation, as prize, of a belligerent or neutral aircraft, all merchandise on board may also be condemned; except that, upon the condemnation of a neutral aircraft, merchandise thereon, not contraband, the property of a neutral other than the owner or operator of the captured aircraft, is entitled to release.
  1. Not printed.