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§ 103 corollary to this would appear to be that the use of a neutral's territorial air will only become a violation of neutrality if persisted in in the presence of aircraft or air forces of the neutral Power. Put in a few words, the position, as above, is in every way analogous to the ordinary law of trespass; the owner is entitled to turn the trespasser off, using only such force as is necessary, and can claim damages only on account of actual injury sustained.

§ 104. ''Other International Questions Relating to Aircraft. Distinctive Marks. It has been suggested, or stated, by most previous writers on the subject that aircraft will be required to carry a distinctive mark or colours, indicating their nationality and their character as military or belligerent—i.e.,'' not civilian—machines. This view is clearly based on the practice which is presumed to obtain in the case of ships-of-war, and which is, to some extent, necessary owing to the fact that the ocean being the common highway of all maritime nations, some declaration of nationality is obligatory, or at least desirable, from the point of view of neutrals as well as of belligerents. History has shown again and again that when a state of war exists, no rules, codified or otherwise, will compel a war-vessel or fleet to display its national flag, or prevent it from using the flag of any other nation that may commend itself at the moment; and if it were not for the interest of neutrals, the practice of employing any distinguishing flag or mark in war-time might fall into desuetude without affecting anything or anybody. Now, in the case of aircraft, it is not only improbable, but quite inconceivable, that civilians or neutrals will be permitted to fly at all in or near the zone