Although the Hague Convention did not make it the duty of the contracting parties to issue manuals for the guidance and informa tion of their naval commanders in the conduct of maritime warfare a number of govern ments have in fact done so. Thus Great Bri tain has her manual of Naval Prize Law, Germany her prize code (promulgated 3 Aug. 1914), which it may be added is not open to the criticism which has been so frequently directed against the German manual of land warfare, and France her "instructions" to the commanders of the naval forces, first issued 19 Dec. 1912, and reissued in revised form 30 Jan. 1916. In 1900 a naval code prepared by Admiral Stockton was promulgated by the Navy Department of the United States but it was withdrawn by President Roosevelt in 1905 and has not been reissued or rePlaced by .an other.
The practice of governments of issuing manuals for the information and guidance of their military and naval commanders marked an important step in the development of the laws of war. The effect was to define and reduce to. written form many of the customs and usages governing the conduct of war on sea and land and thereby remove or reduce the possibility of harm which might result from ignorance or uncertainty on the part of com manders as to what was permissible and what was forbidden by them.
The capital defect of these manuals, how ever, lay in the fact that being unilateral acts they were binding only upon the commanders and troops of the government which issued them and might be altered or revoked at any time. In short, they had no international bind ing effect. What was needed to complete the process of development of which they were the starting point was an international code con taining an authoritative definition and state ment of the laws of war formulated and adopted by the whole body of states, which therefore would be binding upon all of them and which could not be altered at the will of any single state.
So far as the law of land warfare is con cerned this need has now been met in a large degree and to a less extent it may also be said of the law of maritime warfare. This change has been brought about by the adoption of a number of international conventions and declarations, through the agency of conferences representing in some cases practically the whole body of states. These acts are the Declarations of Paris of 1856 and of Saint Petersburg of 1868, the Geneva Conventions of 1864 and 1906 and the Declarations and Conventions of the two Hague Conferences of 1899 and 1907.
The Declaration of Paris of 1856 represented the first attempt to embody in an international act certain rules regarding maritime warfare. It declared privateering to be abolished, estab lished the immunity of private property, except contraband, from capture at sea, when found under a neutral flag and proclaimed that a blockade to be legal must be effective, that is, it must be maintained by a sufficient number of vessels to make the violation of the blockade hazardous to any ship which should undertake to pass the blockading cordon.
The declaration was framed by representa tives of Austria, France, Great Britain, Prussia, Russia, Sardinia and Turkey. At the outbreak of the War of 1914 the only maritime powers which had not formally ratified or adhered to the declaration were the United States, Spain, Mexico, Venezuela, Bolivia and Uruguay. In practice the United States and Spain acted in accord with its rules during the Spanish American War of 1898 and at the second Hague Conference in 1907 the delegations of Mexico and Spain declared that their govern ments accepted the declaration in entirety. Its rules may therefore be now regarded as a part of the body of international law govern ing the conduct of maritime warfare.
Eight years after the adoption of the Dec laration of Paris, that is, 1864, a conference representing 16 states met at Geneva and framed the first Red Cross Convention, the purpose of which was to create certain immunities for the persons who are charged with the care of sick and wounded soldiers in war and for the hospitals, ambulances and material employed in such service. Within a period of four years nearly all the governments of Europe and America had become parties to the convention. In 1906 it was revised and improved by a second conference which also met at Geneva.
In the meantime, 1868, the Declaration of Saint Petersburg was framed by a conference representing most of the governments of Eu rope. The parties to the declaration engaged to refrain from using a certain type of bullet which reason of character inflicted super fluous injury upon those against whom it was employed. The declaration also affirmed the humanitarian principle that there are limits at which war ought to yield to the requirements of humanity, asserted that the only legitimate object which states should endeavor to accom plish during war is to weaken the military forces of the enemy and declared that this object would be exceeded by the employment of arms which needlessly aggravate the suffer ings of disabled men or render their death inevitable. The principle thus laid down, al though criticized by some militarists like von Moltke, has been affirmed by the military manuals of many countries, and was incorpo rated by reference in article 23 of the Hague Convention respecting the laws and customs of war.