[Footnote 53: International Law (1880), pp. 579-580.] Oppenheim shows that the importance of horses and beasts of burden for cavalry, artillery, and military transport sufficiently explains their being declared contraband by belligerents. He asserts that no argument against their being held as conditional contraband has any validity, and it is admitted that they are frequently declared absolute contraband.[54] During the Russo-Japanese War Russia at first refused to recognize any distinction between conditional and absolute contraband, but later altered her decision with the exception of "horses and beasts of burden," which she treated as absolute contraband. [Footnote 54: International Law, Vol. II, p. 426.] The tendency in modern times, however, is to treat horses as only conditional contraband. The only reason that they were not expressly declared contraband in the Anglo-Boer contest was the character of the war. Had the Transvaal been able to issue an authoritative declaration and insure respect for it by a command of the sea, horses and mules would have been considered technical contraband as in fact they were actual contraband, being nothing if they were not "warlike instruments." The enforcement of the obligations incumbent upon the United States under the circumstances undoubtedly lay with the Federal Government rather than with the States. Early in 1901 a proceeding in equity had been instituted in a federal court in New Orleans for the purpose of enjoining the shipment of horses and mules from that port to Cape Colony. The bill was filed by private individuals who alleged that they had property in the Transvaal and Orange Free State which was being destroyed by the armies of Great Britain, and that these armies were able to continue their work of destruction only by means of the supplies of horses and mules which were shipped from the port of New Orleans. The application for an injunction was denied on the ground that the enforcement of the treaty obligations of the Government is a function of the President with which the courts have nothing to do.