This agreement was adopted by Austria, France, Great Britain, Prussia, Russia, Sardinia and Turkey, and it was further agreed that a general invitation to accede should be extended to all nations, but with the proviso “that the powers which shall have signed it, or which shall accede thereto, shall not in future enter into any arrangement, concerning the application of the law of neutrals in time of war, which does not rest altogether upon the four principles embodied in the said declaration[241].”  In other words it must be accepted in whole, and not in part, and the powers acceding pledging themselves not to enter into any subsequent treaties or engagements on maritime law which did not stipulate observance of all four points.  Within a short time nearly all the maritime nations of the world had given official adherence to the Declaration of Paris.

But the United States refused to do so.  She had long stood in the advance guard of nations demanding respect for neutral rights.  Little by little her avowed principles of international law as regards neutrals, first scoffed at, had crept into acceptance in treaty stipulations.  Secretary of State Marcy now declared, in July, 1856, that the United States would accede to the Declaration if a fifth article were added to it protecting all private property at sea, when not contraband.  This covered not only cargo, but the vessel as well, and its effect would have been to exclude from belligerent operations non-contraband enemy’s goods under the enemy’s flag, if goods and ship were privately owned.  Maritime warfare on the high seas would have been limited to battles between governmentally operated war-ships.  Unless this rule were adopted also, Secretary Marcy declared that “the United States could not forgo the right to send out privateers, which in the past had proved her most effective maritime weapon in time of war, and which, since she had no large navy, were essential to her fighting power.”

“War on private property,” said the Americans, “had been abolished on land; why should it not be abolished also on the sea?” The American proposal met with general support among the smaller maritime nations.  It was believed that the one great obstacle to the adoption of Marcy’s amendment lay in the naval supremacy of Great Britain, and that obstacle proved insurmountable.  Thus the United States refused to accede to the Declaration, and there the matter rested until 1861.  But on April 17 Jefferson Davis proclaimed for the Southern Confederacy the issue of privateers against Northern commerce.  On April 24 Seward instructed representatives abroad, recounting the Marcy proposal and expressing the hope that it still might meet with a favourable reception, but authorizing them to enter into conventions for American adherence to the Declaration of 1856 on the four points alone.  This instruction was sent to the Ministers in Great Britain, France, Russia, Prussia, Austria, Belgium, Italy, and Denmark; and on May 10 to the Netherlands.