In April 1861, the commanders in chief of both the United States and Confederacy issued far ranging proclamations. Abraham Lincoln declared a blockade of Confederate ports while Jefferson Davis issued a call for privateers to make war on US seaborne commerce. Oddly, the 1856 Paris Declaration, a document neither president assented to, influenced these actions and the Civil War’s naval aspects by establishing rules both sides were compelled to observe.
Signed in 1856, the Paris Declaration settled issues resulting from the Crimean War. Great Britain dominated the declaration’s formation, with the document tailored to favor Queen Victoria’s government. It included four provisions:
- Civilian operated privateers attacking enemy commerce was abolished.
- Goods owned by a belligerent power could be safely transported on neutral ships, except contraband of war.
- Civilian merchants flying the flag of a belligerent nation were not subject to capture if carrying cargo from a neutral country, unless that cargo was war material.
- Blockades, to be binding, must be effective and maintained by a force sufficient to prevent access to the coast of the enemy.
The United States refused to sign the Paris Declaration, believing it would weaken their ability to fight a future war against European powers by limiting opportunities of U.S. seamen to man and operate privateers. This was a tactic historically used by the weaker United States against British naval supremacy in its Revolution and the War of 1812. Willingly giving up the practice might weaken the United States in future conflicts. Great Britain and France, however, expected U.S. adherence to the document as the Civil War escalated.
Britain, France, Spain, the Netherlands, and Brazil acknowledged Confederate belligerent status in international law, which among other provisions, granted their warships equal status with recognized national navies. Maintaining these belligerent rights, hoping for future recognition as an independent nation, motivated the Confederacy to largely abide by the declaration’s requirements. In July 1861, Jefferson Davis met with his cabinet, which collectively “agreed as two of the points” regarding neutral shipping and cargo, and that the new country “would hold ourselves responsible . . . for the tortuous conduct of our privateers.”
As written, the declaration favored stronger powers over weaker ones, and with the United States acting in a position of strength compared to the Confederacy, the Lincoln administration sought to capitalize. As fighting commenced, U.S. Secretary of State William Seward dispatched notes to Britain and France offering “proposed accession” to the declaration, wishing that signing would outlaw Confederate privateers and protect U.S. merchants. Britain agreed that the United States could sign the declaration, but since hostilities had commenced, they would not hold the Confederacy to “the doctrine of no privateering” The Lincoln administration rejected this stipulation, refusing to sign, but generally adhered to the declaration’s provisions throughout the war.
The Confederacy issued letters of marque and reprisal, sanctioning privateers to attack U.S. commerce. These principally struck in the war’s early months before the blockade became effective, though instances of Confederate privateering continued into 1863 and beyond. Navy Secretary Mallory replaced privateers with commissioned commerce raiders. The United States also debated sanctioning privateers, but decided against it. Instead, Abraham Lincoln’s government called for the execution of captured privateersmen as pirates. Jefferson Davis countered by ordering retaliatory executions of prisoners of war should any privateering sailors face the hangman’s noose, creating a standoff where Confederate privateers were classified as prisoners
Besides a growing effectiveness in the U.S. blockade, Confederate privateering waned because of European influence. Though the Confederacy was not required to abide by the Paris Declaration’s privateering moratorium, Great Britain, followed by other nations, refused to allow privateers and commissioned commerce raiders “from carrying prizes” into British “ports, harbors, roadsteads, or waters.” With foreign ports closed to process captures, civilian privateers were forced to operate close to Confederate ports to bring their captures to an admiralty court for adjudication and eventual payment of prize money. Without a court’s condemnation of a prize, there could be no sale. Commerce raiders, whose crews also could earn prize money, were compelled to destroy their captures.
The Paris Declaration’s neutral cargo and vessel clauses also impacted wartime activity. Confederate Navy Secretary Stephen Mallory freely acknowledged “enemy property not contraband of war, is protected by neutral flag, & that neutral property under enemy’s flag cannot be confiscated as prize” Foreign vessels could be stopped and searched if suspected of carrying wartime contraband intended for a belligerent. U.S. warships occasionally challenged neutral cargo, especially near the Mexican border with Texas and sporadically against British Caribbean shipping. Foreign nations protested this activity in Latin America, a reversal of how the United States protested comparable British activity in the U.S. Revolution and War of 1812, but a handful of international incidents never escalated diplomatic tensions to overt conflict.
The most significant clause of the declaration concerned blockades. It was adamant in the requirement that a formal blockade be effective. While neither the U.S. or Confederacy were signatories, both the British and French demanded an effective and continuous blockade of the Confederate coastline. If the U.S. Navy failed to maintain one, European powers could nullify the blockade and flood Confederate ports with critical supplies. Many Confederates hoped Britain would recognize their nation and the Royal Navy would disperse blockading ships. In declaring a blockade, the United States was legally strongarmed into effectively maintaining it to deter European powers from overtly assisting the Confederacy.
The Confederacy realized a nullified blockade would benefit their attempts at international legitimacy and the country’s naval forces repeatedly sought to breach the blockade in the hopes of attaining foreign recognition. An improvised Rebel squadron dented, but failed to pierce, the blockade of the Mississippi River at the battle of the Head of Passes in October 1861. In March 1862, CSS Virginia struck blockaders at the battle of Hampton Roads but was stopped by USS Monitor’s timely arrival. In January 1863, the Confederacy’s Charleston naval squadron of two ironclads dispersed that city’s blockade. Confederate diplomats claimed a formal breach of Charleston’s blockade, though U.S. warships reestablished their cordon around the harbor the next day and an official breach was never recognized.
Britain and France tracked the Paris Declaration’s de-facto wartime enforcement directly, even contemplating intervention at sea to appease European textile manufacturers dependent on Southern cotton. Though Britain never formally intervened, Admiral Sir Alexander Milne, Commander-in-Chief, British North America and West Indies Station, instructed his captains regarding the Paris Declaration’s enforcement. This guidance included orders to “afford the greatest possible protection to lawful British Commerce,” and to “adopt every possible lawful measure to protect British ships from molestation by … Privateers.” Most specifically, Milne instructed captains to steam along the Atlantic seaboard “for observation” of the blockade, documenting “all Blockading Squadrons” and “whether they are, in each case, adequate to maintain efficiently the Blockade.”
Other European powers inspected the blockade. The French frigate Milan was present at the Mississippi River’s mouth as David Farragut’s Western Gulf Blockading Squadron advanced upriver in the 1862 New Orleans campaign. On the Virginia coastline, the British warship HMS Rinaldo and two French war steamers were anchored in the Chesapeake Bay immediately after the battle of Hampton Roads, observing the blockade despite CSS Virginia’s sortie. Ultimately, the blockade remained legally effective throughout the war, even if most individual blockade-running trips defied it. This allowed the Lincoln administration to maintain its de-facto agreement to abide by the Paris Declaration, even though it did not formally acquiesce to the treaty.
The 1856 Paris Declaration proved the most influential document of international maritime law impacting the Civil War, which is astounding considering that neither the United States nor Confederacy were party to the agreement. The diplomatic and naval strength of Great Britain, and the desire of both sides to curry favor of Queen Victoria’s government and people, ensured that the declaration impacted wartime operations by limiting privateering and encouraging Confederate commerce raiding, establishing rules for neutral ships and cargo, and forcing the application of an effective and constant blockade.
 Declaration Respecting Maritime Law, Signed by the Plenipotentiaries of Great Britain, Austria, France, Prussia, Russia, Sardinia, and Turkey, Assembled in Congress at Paris, April 16, 1856 (London, 1856), 4.
 Stephen R. Mallory Diary, July 26, 1861, Vol. 1, Southern Historical Collection, The Wilson Library, University of North Carolina at Chapel Hill.
 Charles Francis Adams, Seward and the Declaration of Paris: A Forgotten Diplomatic Episode, April – August 1861 (Boston, 1912), 26.
 August 23, 1861, Diary of Charles Francis Adams, 1823-1880, Adams family papers, Massachusetts Historical Society.
 Mountague Bernard, A Historical Account of the Neutrality of Great Britain During the American Civil War (London, 1870), 136.
 Mallory Diary, July 26, 1861, Vol. 1.
 James P. Baxter, ed., “Papers Related to Belligerent and Neutral Rights, 1861-1865,” The American Historical Review, Vol. 34, No. 1 (Oct. 1928), 78-80.