On the conclusion of the Treaty of Paris on 30 March 1856 which ended the Crimean War (1853-1856), the Plenipotentiaries also signed the present Declaration. It is the outcome of a modus vivendi which was adopted between France and the United Kingdom in 1854 and was originally intended for the Crimean War. Both Powers recognized that they would not seize enemy goods on neutral vessels nor neutral goods on enemy vessels. The belligerents furthermore proclaimed that they would not issue letters of marque. The Declaration of Paris confirmed these rules and added to them the principle that blockades, in order to be binding, must be effective. Virtually all States acceded to the Declaration. The United States, which aimed at a complete exemption of private property from capture at sea, withheld its formal adherence, its amendment not having been accepted by all the Powers. In 1861, at the beginning of the Civil War, the United States announced nevertheless that it would respect the principles of the Declaration for the duration of the hostilities.
Equally, in 1898 during the war against Spain, it was affirmed that the policy of the government of the United States would be to abide by the provisions of the Declaration throughout the hostilities. The rules laid down in the Declaration were later considered as part of general international law and even the United States, which is not formally a party thereto, abides by its provisions.