The so-called Quasi-War with France lasted until 1801. President Adams wisely took advantage of a change in the French government and negotiated the Convention of 1800, destroying his chances at reelection in 1796. Many Federalists, including Hamilton, who sought a war with France and an Anglo-American rapprochement, felt betrayed by Adams. The convention abrogated the 1778 alliance with France, but retained the commercial provisions and liberal definition of neutral rights characteristic of the earlier commercial treaty. This agreement, together with the Peace of Amiens (1802) that temporarily ended the European war, enabled the United States to pursue a course independent of the European conflict while at the same time maintaining its neutral rights. Under the provisions of the Convention of 1800, the interdiction on American trade pertaining to all countries except Great Britain and France was removed, and the president was authorized to permit trade with the two great powers if they should cease violating the neutral trade of the United States. However, with the resumption of war between Great Britain and France, and its expansion by 1805 with the formation of the Third Coalition against Napoleon, each side sought to gain advantage by shutting off the other's trade. In this deadly duel between the leading belligerents, neutral rights were once again neither recognized or respected.
In 1805, in the case of the Essex, a British admiralty court ruled that the practice by which American ships carried goods from French colonies to France, with only a brief stop in an American port, did not constitute a broken voyage but, in reality, was a continuous voyage. Thus, French goods were not neutralized and were therefore subject to seizure. Consequently, Britain passed a series of orders in council designed to impose a blockade of all ports controlled by France, thereby forcing American vessels to go first to Great Britain, pay fees, and allow their goods to be subject to search and seizure. France retaliated with its Berlin and Milan Decrees, placing an embargo on all trade with Britain, and ordering the seizure of all ships that had paid the fees demanded by the Orders in Council, arguing that neutral vessels which did so were no longer neutral but British, and thus liable to seizure. Subsequent decrees also allowed for the arrest of American ships in ports controlled by France and the confiscation of their cargoes. These and subsequent acts and other retaliatory measures by both belligerents, although primarily directed toward each other, nonetheless violated American rights and severely threatened American trade with Europe and its colonies. Lacking effective military and naval power to protect its shipping, the United States attempted through negotiations with Britain, and peaceable economic coercion directed at both Britain and France, to force both belligerents to respect American neutral rights. The Monroe-Pinkney Treaty (1806) with Britain failed to achieve guarantees for American neutral rights. In fact, so unsatisfactory was the treaty that President Thomas Jefferson refused even to submit it to the Senate for ratification.
Calculating that American trade was essential to the British, and to a lesser extent to the French, the United States employed coercive measures, beginning with the Non-Importation Act of 1806. This measure prohibited certain British manufactures from being exported to the United States. In 1807 Jefferson imposed the Embargo Act, a measure that prohibited American ships from leaving American ports. Although many American merchant vessels failed to adhere to the embargo, particularly as time elapsed and it failed to achieve its objectives, the embargo still severely restricted American trade, caused a depression, and produced intense political and sectional feelings in the country. In 1809 British minister David Erskine negotiated the Erskine Agreement with the United States, and President Madison prematurely lifted the embargo. When the treaty reached England, it was repudiated by the British government and Madison, somewhat humiliated, was forced to reimpose the embargo.
In 1809, under severe economic and political pressures, the Madison administration replaced the Embargo and the Non-Importation Act with a watered-down version of the embargo known as the Non-Intercourse Act. This measure opened trade to the world, except for Britain, France, and their possessions. In 1810 the Non-Intercourse Act was replaced by Macon's Bill No. 2, which reopened trade with even Britain and France, but stipulated that if one belligerent rescinded its restrictive measures, the United States would then impose nonintercourse against the other. When Napoleon's government implied that it was rescinding the Continental Decrees against American commerce, Madison jumped at the promise on face value when, in reality, France continued to seize American ships and cargoes. As Britain refused to rescind its orders in council when evidence confirmed that France had not actually stopped violating American neutral rights, Madison issued a proclamation, backed by the Non-Importation Act of 1811, prohibiting British goods from being imported into the United States.
Although the United States resented both Great Britain and France, the issues with the British were more long-standing and had greater impact. Many factors contributed to the War of 1812 with Britain, but certainly violation of American neutral rights, impressment of American seamen, and defense of national honor were major contributing factors. The war ended with neither belligerent achieving its expressed purposes. However, the establishment of peace and the conclusion of an Anglo-American treaty of commerce, as well as an agreement to limit naval armaments on the Great Lakes and to settle boundary and fisheries disputes, launched a new relationship between the two nations. After the Treaty of Ghent of 1814, which ended the war with Britain, and the conclusion of the Napoleonic Wars in 1815, there were no major maritime wars for the rest of the century. Thus ended an epoch in the American struggle for neutral rights.
A new phase in the American policy of neutrality was brought about by revolutions in the colonies of Spanish America. Officially, the United States did not play a role in these revolutions and was not particularly concerned about them until such time as any had established permanent governments and therefore warranted recognition as independent states. However, when it looked like one or more European powers might assist Spain in restoring its American empire, President James Monroe in 1823 issued a message to Congress, largely written by Secretary of State John Quincy Adams, that came to be known as the Monroe Doctrine. In essence, Monroe's message was a reaffirmation of the Doctrine of the Two Spheres. It also announced that while the United States would refrain from involvement in European affairs, it opposed any further European colonization of the Western Hemisphere, an extension of Europe's political systems to American states, or efforts to interfere in their internal affairs. Although Congress did not confirm the Monroe Doctrine and there was no occasion that developed immediately to test it, it became a cornerstone of American foreign policy and a justification for future acts that attempted to establish U.S. hegemony in the Western Hemisphere in the decades to follow.
From 1823 until the American Civil War, the United States had no serious problems regarding neutrality. It officially maintained a neutral position during the Texas War for Independence (1835–1836) and the Canadian Uprising of 1837. During the Mexican War (1846–1848) the United States was able to establish an effective, and therefore legal, blockade of Mexican ports. When the Crimean War broke out in 1854, Britain and France agreed to a set of principles that were later codified and proclaimed by the leading European nations as the Declaration of Paris of 1856. This declaration acknowledged the long-standing American position that free ships make free goods, and that a blockade must be effective to be legal. It also contained the principles that noncontraband goods on enemy ships should be free from capture and that privateers should not be commissioned. As the United States was unwilling to surrender its right to commission privateers, and as it hoped to secure an additional agreement that all private property except contraband would be free, it failed to endorse the declaration. Ironically, after the outbreak of the American Civil War in 1861, the United States agreed to adhere to the declaration if its provisions were applied to the Confederacy. This offer was rejected by such nations as Britain and France.
The beginning of the Civil War saw the United States in an anomalous situation regarding its position on neutrality. War was not declared against the Confederacy, nor was belligerent status accorded it. Rather, the administration of Abraham Lincoln considered Union military operations to be a police action against rebellious citizens. Given this view, when Lincoln proclaimed a blockade of Confederate ports on 19 April 1861, it was a domestic action and did not have to be effective in order to be legal. However, when Britain declared neutrality on 13 May 1861, it in effect granted the Confederacy belligerent status that, among other things, meant Britain would consider a blockade of Confederate ports subject to the usual rules of international law. Since the United States did not have sufficient naval power to make the blockade effective until later in the war, the Confederate government, while also pursuing diplomatic recognition, hoped that European nations would challenge the blockade's legality. This did not occur, however, largely because Great Britain concluded that its long-term interests would be best served by accepting the Union interpretation of a blockade's effectiveness. Before the end of the war, Confederate trade with Europe was almost completely stifled because of superior Union naval strength and the capture of major Confederate ports.
In addition to its position on blockade, the United States adopted the doctrine of continuous voyage, a principle taken from British prize law: a ship carrying contraband goods for a belligerent could be captured on the high seas in voyage from a neutral port to another neutral port whenever such a port was only a way station and not the ultimate destination of the cargo. The adoption and use of this doctrine by the United States established a precedent in American policy that was useful to Britain and the Allies in their conflict with the Central Powers when the United States was still a neutral state prior to its entry into World War I.
One incident occurred during the Civil War that caused the British to assert their rights as a neutral. This was the Trent affair of 8 November 1861, when an American naval vessel on the high seas stopped a British mail steamer, the Trent. On board were two Confederate diplomats on their way to England. The ship was boarded and the two diplomats were arrested and sent to prison in Boston. News of this violation of British neutral rights produced an immediate response from the British government, which demanded the release of the Confederates and an apology. For a short time there was even talk of war as the British undertook preparations. On the American side, with no desire for war with Britain given its pre-occupation with the challenges of civil war, Secretary of State William H. Seward acquiesced to British demands and conflict was averted.
Aside from the Trent affair, the most significant conflict over neutral rights and duties during the Civil War was the construction and outfitting of warships (designed to be commerce raiders). This was significant primarily in relations between the United States and Britain, whose laws permitted—as did international law—the sale of merchant ships to belligerents, but prohibited the sale of warships. The Confederacy sought to circumvent this prohibition by having vessels built ostensibly as merchant ships, but constructed in such a way so as to be easily converted into warships at sea or in a Confederate port. The most notorious case, albeit not the only one, was the Confederate cruiser Alabama. The United States contended that Great Britain had failed to live up to its obligations as a neutral by allowing the Alabama to leave British waters. The British government asserted that the Alabama was a merchant vessel until it was significantly altered and equipped with naval armament in a Confederate port. This controversy continued throughout the Civil War, and was not resolved until the Treaty of Washington in 1871. In addition to the United States being awarded $15.5 million by an international tribunal, the significance of the treaty was in the concession by Great Britain that a neutral had an obligation to use "due diligence" in preventing a ship from being built "in whole or in part" as a warship for a belligerent. Although only signatories were bound by the treaty, the principle was subsequently incorporated in a convention on the rights and duties of neutrals at the Second Hague Conference (1907), the difference being that the imprecise rule of "due diligence" was changed to the obligation of a neutral to use the "means at its disposal."