The Law of Nations in the Diplomacy of the American Revolution

Abstract

Historians have long known that leaders of the American Revolution looked to the law of nations for insight into the rights and obligations of independent states. In so doing, Americans relied largely on the writings of European legal theorists, such as Hugo Grotius and Emerich de Vattel, whose treatises on the law of nations are regarded today as having laid the foundations of international law. As this article demonstrates, however, early modern statesmen did not base their conduct on such treatises, but on a customary law of nations that they derived from precedent and the text of earlier treaties. This article elucidates the distinction between the customary and theoretical branches of the law of nations. It then goes on to examine the law of nations’ impact on revolutionary-era diplomacy, drawing particular attention to a series of wartime negotiations over rights to the Mississippi River. As the article shows, most American emissaries lacked experience with the customary laws of diplomacy and struggled to use that law effectively in their negotiations. The most serious consequences were averted due in part to French legal advice, and because one American, John Jay, acquired enough competence in customary law to guide his colleagues toward an effective negotiation of peace.

In an oft-quoted letter from 1775, Benjamin Franklin thanked a friend in Europe for having sent over three copies of Emerich de Vattel's recent treatise, The Law of Nations (1758)—one of which Franklin circulated among members of the Continental Congress. “It came to us in good season,” Franklin wrote, “when the circumstances of a rising State make it necessary frequently to consult the law of nations.” What was this “law of nations” to which Franklin referred, and how was it relevant to the needs of the early United States? Historians generally answer that question by reference to the treatises of European legal theorists such as Vattel (1714–67), Hugo Grotius (1583–1645), or Samuel von Pufendorf (1632–94). Their writings were admired by leaders of the American Revolution, who looked to them for insight into European conceptions of law. Recent scholarship has shown that the law of nations influenced the Declaration of Independence, the United States Constitution, and the early federal judiciary. As Alexander Hamilton wrote in 1795: “Ever since we have been an Independent nation, we have appealed to and acted upon the modern law of Nations as understood in Europe.”¹

This essay broadens the inquiry by asking how the law of nations affected the conduct of early American diplomacy. In so doing, it draws needed attention to a facet of the law that has received little attention in the scholarly literature: the customary law of nations. The customary law of nations was a body of pragmatic norms and conventions that European statesmen had developed over the course of centuries as a means of resolving conflict in the political or interstate realm. Dating back to the medieval era, it encompassed the laws of war, navigation, commerce, and diplomacy, and derived its authority from precedent and the consent of European sovereigns. The treatises of Vattel and others, by contrast, were academic commentaries on the law that dealt principally with its philosophical foundations. They were widely respected and occasionally consulted, but it was customary law that governed the political arena.²

There are at least three reasons that the customary law of nations has received little scholarly attention to date. First, it was largely concerned with procedural aspects of statecraft that rarely played a determinative role in political events. Second, although facets of customary law were codified in the text of European treatises, most of it was unwritten and learned through experience, making it difficult to recover apart from a laborious survey of state papers. Finally, it was influenced by power dynamics and political compromise to such an extent that it is of little interest to scholars working on the antecedents of modern international law—especially when compared with the ideals of Vattel and his fellow philosophers.³

Yet it was the customary law of nations that undergirded the conduct of early modern statecraft, and its existence raises the question of why the Americans relied on the treatises of Vattel et al. if they carried so little weight in the diplomatic realm. Part of the answer lies in the treatises’ legal ideals, which helped the Americans to draft documents like the Declaration of Independence. A weightier reason stems from the revolutionaries’ dearth of experience with European diplomacy. When the revolution began in 1775, no one on the American side had ever conducted formal diplomacy—that realm being the exclusive purview of sovereign states. They had negotiated with American Indians and with British officials in a domestic context, and they were expert in commerce and the laws of navigation. But they had never conducted affairs of state. As John Jay wrote in 1787, “Prior to the revolution we had little occasion to enquire or know much about national affairs, for although they existed and were managed, yet they were managed for us, but not by us.”⁴

The Americans looked to the theoretical treatises then, in part to compensate for their lack of diplomatic experience. For reasons already noted, the treatises were of little help in this regard, and Americans struggled throughout the war to use law effectively in their negotiations. In a recent article for the Journal of the American Republic, I made this point vis-à-vis the negotiation of the Treaty of Paris (1783)—demonstrating the Americans’ propensity for error, while also pointing to John Jay as an exception to the rule and as perhaps the only American of his generation to exhibit competence in the use of customary law. This essay broadens that argument in two respects. It first traces the development of the customary and theoretical branches of the law of nations over the course of European history. It then reviews the impact of customary law on a wider range of revolutionary-era negotiations, placing particular emphasis on a Spanish–American dispute over rights to the Mississippi River that also culminated with the Treaty of Paris.⁵

The Law of Nations in Theory and in Practice

The term “law of nations,” or ius gentium in Latin, first emerged during the era of the Roman Republic, where it referred to laws governing peoples outside the bounds of Roman civil law. During the later imperial era, jurists like Cicero also began to use the term in relation to principles of natural law, such as the duty of good faith, that pertained to all of humanity. This nascent distinction between pragmatic and philosophical facets of the law of nations then carried over into the Middle Ages where the term came to be used in relation to political and military activities such as: “fortification, war, captivity, servitude, postliminy, treaties, armistices, truces, the obligation of not harming ambassadors.”⁶

During the Middle Ages, the law of nations did not yet pertain to “states” per se, but rather governed a variety of political actors who operated under the juridical oversight of the Roman Catholic Church. Nor did the law of nations yet constitute a distinct body of law in its own right. It was rather a term used in relation to a variety of norms that were themselves derived from one of the three main bodies of European law: church canon law, Roman civil law, and feudal customary law. Norms that were derived from feudal customary law carried the greatest weight in the political realm, while church theologians and other scholars used canon law and civil law to work out the foundations of theoretical concepts such as: sovereignty, the sanctity of treaties, and the rights of non-combatants. Church theologians influenced the political realm insofar as church officials relied on their opinions in mediating disputes, yet their reach was limited. As Donald Queller has written, “esteemed theorists, such as Thomas Aquinas and Christine de Pisan simply did not know very much about diplomatic practice,” and many of their most famous theories were not reflected in medieval statecraft.⁷

The process by which the law of nations became a distinct law of sovereign states began during the sixteenth century. Credit for initiating the shift in the intellectual realm is often given to Francisco de Vitoria (1483–1546). Vitoria was a Dominican priest who was looking for a law that could govern relations between Spain and the indigenous people of the Americas. In his seminal essay, De Indis (1532), he invoked Cicero's sense of the law of nations as a universal law of nature, and called upon European sovereigns to obey its dictates. In the decades that followed, other theorists such as Francisco Suárez (1548–1617) and Alberico Gentilli (1552–1608) gave fuller expression to Vitoria's idea, while also popularizing his notion of a law of nations rooted in natural law. Left unanswered, however, was the practical question of how this new conception of the law of nations could be reconciled with the law of nations as it already existed in Europe. I.e., which facets of the extant law of nations met the new criteria?⁸

That question was famously answered by Hugo Grotius in his magnum opus, On the Law of War and Peace (1625). Writing in the midst of the Protestant Reformation, Grotius was looking for a non-sectarian basis for the law of nations—free from the influence of theology—to govern a Europe now rent by theological schisms. With that goal in mind, Grotius took Vitoria's concept of a natural law of nations and paired it with a new method for deriving the natural laws of war and diplomacy. Surveying the historic record, Grotius argued that any law held coincidentally by every (or nearly every) state in antiquity was, by implication, a universally binding law of nature. Grotius then put this new method into practice by offering his learned opinion on a host of practical questions, such as when a state might lawfully declare war, and how war ought to be conducted once begun.⁹

In the decades that followed, other theorists in northern Europe, including Samuel von Pufendorf (1632–94), Christian Wolff (1679–1754), Jean Jacques Burlamaqui (1694–1748), and Emerich de Vattel (1714–67), built on Grotius's idea, while also modifying his method for deriving the law of nations from the law of nature. By the late eighteenth century, treatises of this kind were embedded in the intellectual life of Europe. They were assigned as works of ethics at colleges and universities. They were cited by English jurists in domestic cases touching on the law of nations. They were also read by some diplomats in northern Europe as part of their training, and were sometimes cited in diplomatic disputes over legal questions such as sovereign rights to the sea. Yet the treatises did not become the embodiment of the law of nations as it governed the political realm. Rather, practitioners continued to rely principally on the customary laws that had been developed during the earlier medieval era.¹⁰

Not only did customary law remain in effect, but over the course of the Renaissance and early modern eras it also began to expand in scope and influence in conjunction with the rise of the nation state. This process of legal development is seldom captured in histories of international law, yet it can be discerned in histories of “diplomatic method,” which describe how during the fifteenth century, city-states on the Italian peninsula began to establish permanent embassies in neighboring courts to monitor political activity. The creation of these embassies gave rise to a host of new norms and protocols, governing matters ranging from: rank and precedence, to privileges and immunities, and the authentication of diplomatic communications.¹¹

Over the course of the fifteenth and sixteenth centuries, the new norms and protocols were adopted throughout Europe by monarchs who were also claiming control over defined territorial states. As an expression of their sovereignty, these rulers began to assert an exclusive right to use the customary law of nations and the norms that it prescribed for the diplomatic realm. As this process unfolded, the law of nations came to function as a code of honor, tied to the person of the sovereign, whose character embodied that of the state. At a conceptual level, the law retained its association with universal natural law—an association now strengthened by the treatises of Grotius, Pufendorf, et al. At a practical level, most customary laws were based on precedent, and their binding obligation derived from the principle of pacta sunt servanda, or “agreements must be kept.” Key facets of customary law were written into the text of major treaties, but the majority of the law remained unwritten and learned through experience.¹²

The Law of Nations in the American Revolution

As noted above, leaders of the American revolution had no experience with formal European diplomacy when war began in 1775, and they struggled at times to employ even the most basic elements of the customary law of nations. An early example can be seen in Congress's reception, in July 1778, of Conrad Alexandre Gérard, the first French envoy to the United States. The reception of a diplomatic envoy was a routine event in Europe, marked by ceremonies designed to affirm the dignity of the respective sovereigns. It took Congress weeks to resolve such basic questions as the size of Gérard's party, the posture that he should adopt when giving his opening speech, and whether he should stand or remain seated when listening to the response of the president of Congress—prompting Gérard to report on, “the very confused notions that they have here concerning the honor, dignity and etiquette of a sovereign State.”¹³

Although protocols of this kind did not play a major role in statecraft, two aspects of customary law did become significant over the course of the revolution. The first had to do with the methods that European statesmen used to resolve disputes over treaty obligations. As noted earlier, the foundation of customary law in the early modern era was the person of the sovereign, whose reputation for integrity provided security for treaties and other agreements. The frequency with which sovereigns violated such agreements has prompted many scholars to disparage the system, yet it was not without constraining effect. All sovereigns needed the assistance of other states, and a reputation for honesty was the basis on which they could obtain such aid or otherwise influence the course of political events apart from war. As the French foreign minister once wrote to his ambassador in Spain, “Remember, Monsieur… if all this should end through an injustice, the King risks less in suffering it than in doing it. Damage to his interests could be repaired; nothing would repay the loss of his reputation.”¹⁴

It was therefore incumbent upon European ministers of state to protect their sovereign's reputation to the greatest extent possible, and especially whenever circumstances required him or her to breach an agreement. Statesmen accomplished that task through the use of pretexts, or public explanations, by which they justified their policies and conduct. They were aided in their efforts by the fact that the law of nations permitted violations of treaties and other obligations for “good reason.” Yet not just any reason would suffice. The use of pretexts was governed by a shared set of norms, and statesmen were adept at evaluating their counterparts’ arguments. They kept records of violations, and retaliated when interests dictated and circumstances permitted. To operate effectively in this realm required knowledge, skill, and experience, as well as keen judgment and a socialized understanding of the law of nations and its underlying principles.¹⁵

An example can be seen in a dispute that arose between France and Spain in early 1780. The year prior, in April 1779, Louis XVI and Carlos III had signed an agreement known as the Convention of Aranjuez, on the basis of which Spain agreed to enter the war against England as an ally of France—though not of the United States. Carlos III had signed the agreement reluctantly, and only on condition that France agree to an immediate invasion of England, which he hoped would bring the war to a rapid conclusion. The invasion failed and by the fall of 1779, Carlos found himself enmeshed in a costly and protracted war with no clear path to victory. In that context, his ministers began to seek a way out of the Convention of Aranjuez.¹⁶

The Spanish court was hindered in its efforts by Article III of the Convention, in which the two sovereigns had promised that they would not, “listen to any direct or indirect proposal on the part of the common enemy without communicating it each to the other.” Despite that promise, the Spanish council of state voted unanimously in February 1780 to commence peace negotiations with England, without informing France. They justified their conduct, and defended the honor of Carlos III, by noting in their minutes that France had done the same thing to Spain at the conclusion of the Seven Years’ War (1756–63). In other words, Carlos III was merely evening the score, and not was committing a new breach of faith.¹⁷

The Spanish council went on to devise a similar pretext that they hoped would relieve Louis XVI of his obligation under the Franco–American treaty of alliance to defend American independence. They suggested to a British agent that if George III would grant the Americans a “vague feudal dependency, like the free Cities of the [Holy Roman] Empire,” Spain would adopt a posture of “useful neutrality” toward the war—thus putting pressure on France to sue for peace. They offered to press this compromise on France, by means of “some casuistical formula,” as constituting “tacit independence” for the United States, thus enabling all parties to exit the war with dignity. The British cabinet rejected the proposal and nothing came of it, yet the attempt still illustrates the importance of reputation, and the skill that was needed to devise and evaluate legal arguments in that environment.¹⁸

The second aspect of the law of nations that became consequential during the American Revolution had to do with the law's role in marking the boundary between state and non-state actors in the European political system. As noted above, during the early modern era, the principal monarchs of Europe had begun to establish sovereignty over defined territorial states, and with it an exclusive right to use the customary law of nations. As those states came into being, the forms and procedures that customary law prescribed for the diplomatic realm came to serve as markers of political legitimacy in that only states were allowed to use them.¹⁹

During the American Revolution, the use of these customary forms became a significant point of contention. The Americans sought to strengthen their claim to statehood by employing these forms in a variety of contexts, while the British resisted those efforts and even sought to lure the Americans into using forms that would concede a subordinate status. Of particular importance were the credentials, or letters of authority, that European diplomats exchanged at the start of their negotiations. The credentials were based on formulae dating back to the medieval era, and were examined with minute care, both for accuracy and to ensure that the respective sovereigns were described in language appropriate to their relative dignity or status.²⁰

The Americans’ inexperience with such matters became apparent during a dispute that arose in the aftermath of the Battle of Saratoga (October 1777). The dispute centered on the convention that the British and American generals had signed at the conclusion of the battle, which established the British terms of surrender. As was customary, the British general, John Burgoyne, had pledged that his soldiers would not take up arms against the United States for the duration of the war, while the Americans had promised to release Burgoyne's army as soon as conveniently possible. Conventions of this kind were not terribly durable, and it sometimes happened that one party would later accuse the other of having violated a provision of the convention, and use the violation as a pretext for voiding the entire agreement. The Americans were therefore concerned when, in December 1777, Burgoyne published an open letter accusing them of having “broken faith” by failing to provide his officers with adequate accommodations.²¹

Congress met in January 1778 to consider the matter. After some deliberation they determined that Burgoyne's word of honor no longer offered sufficient security. His army would have to remain in captivity until the British government had ratified the convention. In April 1778, the British government sent a peace commission to North America. The commissioners’ primary task was to forestall the effects of the Franco–American treaty of alliance, which had been signed in February of that year, but they also carried credentials that purportedly authorized them to ratify the convention of Saratoga. The commissioners reached New York in June. Shortly thereafter they sent copies of their credentials to Congress and asked for a response.²²

The members of Congress were in the process of drafting a reply when Conrad Gérard arrived in Philadelphia. The Americans briefed him on the matter and asked for his advice. Gérard immediately noted problems with the British credentials that the Americans had overlooked. First, the credentials had been signed by Parliament rather than by George III, who “by his prerogative and by the constitution,” had an exclusive right “to negotiate” with other states. More significantly, the credentials were drafted in a style suitable for domestic transactions rather than those between independent states. For the Americans to proceed on the basis of such letters, Gérard declared, or “under any other titles than those that the law of nations and the usage of sovereign Powers admitted… would be to permit a shameful mark of Subordination.” The Americans, he concluded, should not even dignify the commissioners’ letter with a response.²³

Gérard's advice had three practical effects. It saved the Americans from conceding a subordinate status. It frustrated British efforts to negotiate peace with the Americans by foreclosing the only method of negotiation (domestic) that George III would accept. Finally, it sealed the fate of Burgoyne's army. Although precedents had been established during the Dutch War for Independence that a sovereign's ratification of a military commission did not constitute a definitive recognition of statehood, Gérard correctly predicted that George III would be unwilling to endorse even a “tacit” recognition of American independence.²⁴

The Mississippi Border Dispute

French legal advice was a boon to the United States when French and American interests aligned. It became problematic, however, when their interests diverged. Among the most serious points of divergence was the American claim to a western border on the Mississippi River. The Americans generally regarded the United States as the natural heir to all British territory west of the Allegheny Mountains. From a legal perspective, they based that claim on charters that the British crown had granted them during the seventeenth century—several of which had no western limits, the size of North America being unknown at the time. Although limits were later established in 1763, when George III ceded the lands west of the Mississippi River to Spain and then forbade his American subjects from settling west of the Alleghenies, the vision of westward expansion was already embedded in the Americans’ minds.²⁵

The revolutionaries had raised this issue with Vergennes prior to the signing of the Franco–American treaty alliance. At the time, Vergennes had accepted the Mississippi border, “as adjusting the matter properly.” Once the terms of the treaty were worked out, however, he came to see the issue in a different light with respect to French legal obligations. The crux of the matter lay in Article XI of the treaty, in which Louis XVI had guaranteed to the United States “thair Possessions, and the additions or conquests that their Confedération may obtain during the war.” Was the trans-Appalachian west a current “Possession” of the United States—in which case France was contractually obligated to perpetuate the war in support of the American claim; or was it a potential “addition or conquest”—in which case France's obligations would only come into effect if the United States acquired the region through war or diplomacy?²⁶

Over the course of 1778, it became clear that Vergennes favored the latter interpretation. For one thing, French finances were in a precarious position, and he knew that Louis XVI could not afford to perpetuate war in support of objectives that were ancillary to American independence. By the fall of 1778, it had also become evident that France needed to take into consideration the strategic interests of Spain. Spain was France's principal ally in Europe and, as noted earlier, Carlos III was initially reluctant to enter the war. In the months leading up to his eventual decision to do so, Vergennes had been actively seeking to entice Carlos III with offers such as the potential acquisition of Florida or Gibraltar.²⁷

At some point in 1778, Vergennes learned that Carlos also desired exclusive navigation rights on the Mississippi River, which he viewed as an effective means of hindering American commerce and discouraging the westward expansion of the United States. Vergennes could not satisfy Carlos’s desire without the Americans’ consent and so he decided to broach the topic with Congress. On October 26, 1778, he wrote to Gérard, asking him to ascertain the Americans’ position vis-à-vis the trans-Appalachian west. Did Congress view the region as an essential objective—without which they would never agree to peace? Or might they be willing to cede some of their claims to enable a rapid end to the conflict? If he found that the Americans held to the former view, Gérard was instructed to “prepare them… with prudence and moderation” for the possibility that they might need to soften their position in order to facilitate Spain's entry into the war.²⁸

Gérard received his instructions in December and promptly broached the subject in an after-dinner conversation with leading members of Congress. Brushing aside the legal ambiguities of the question, he framed the issue squarely in terms of the Americans’ national honor. “[A]ll Europe,” he declared, “suspected them of having inherited the invasive and unruly spirit of their ancestors.” He urged them to deal preemptively with that problem by drawing “a permanent line of separation between Spain's possessions and their own.” In no better way, he argued, could they “convince the universe of their justice and pacific system,” and “establish their character,” while also restraining “the ambition of their posterity.”²⁹

A few weeks later, at a special session convened on February 16, Gérard made a similar argument before the entire Congress. The war, he argued, “had but one sole fundamental and essential object, that of the independence of the States.” Louis XVI, “had no ambitions of Conquest” while Carlos III sought only “to administer well the states that Heaven had given him.” It was to that end alone, Gérard continued, and “to secure his borders and prevent all trouble with his neighbors,” that the Spanish king desired “the Exclusive Navigation of the Mississippi.” Moreover, Gérard warned, England would “be revolted” if the Americans should instead demand, “without title or right, concessions other than the integral parts of their States.”³⁰

When the members of Congress did not immediately yield to these arguments, Gérard shifted his rhetorical focus to the honor and character of Louis XVI. The French king, he averred, had struggled before agreeing to the alliance, to “convince himself of the justice of the American cause.” What would he think now if he heard that the United States “demanded possessions to which [they] had no rights?” Making his “lamentations full of feeling,” Gérard warned of the consequences that would befall the new nation if they should lose “all character” so early in their existence, and give “to their reputation a strong tint of ambition and avidity.”³¹

A majority of Congress understood their interest in the Mississippi well enough to resist Gérard's rhetoric; yet they struggled to defend their position with language or principles that aligned with European sensibilities. In early April, a group of representatives met privately with Gérard to ask for his help in resolving a related dispute over American claims to the Newfoundland fisheries. “The majority of them,” they told Gérard, “were ignorant of the most basic elements [of the issue].” They “begged [him] to instruct them on the true principles of the matter, of the usages and rules established between the Powers of Europe, i.e. of the real situation of things.” Gérard was only too happy to oblige, doing so again in a way that favored French interests.³²

The debate over the Mississippi continued until August, when Congress finally voted to make the Mississippi border a sine qua non of peace, while also sending emissaries to Europe to resolve the dispute directly with the relevant courts. John Adams was appointed United States’ Commissioner of Peace, and tasked with representing the United States at any future negotiations with Great Britain. John Jay was chosen as American minister to Spain, and sent to Madrid with instructions to seek Spanish recognition of American independence, a loan, and resolution of the dispute over the Mississippi.³³

American Emissaries Abroad

If the Americans’ dearth of experience with customary law was consequential in Congress, it became all the more so in Europe where Adams and Jay had to act without the advice and support of their peers. Adams had the greater difficulty of the two. Within months of his arrival in Paris, he so thoroughly offended Vergennes that he undermined his standing in France, and with it the authority of the larger American diplomatic corps. The precipitating issue was a set of ancillary instructions that Congress had given Adams, to negotiate a treaty of commerce with Great Britain after peace had been established. Adams wanted to publish those credentials immediately on arrival in Europe, arguing that Great Britain would view the Americans’ willingness to discuss commerce as a gesture of good will. Vergennes urged Adams to wait, noting that peace negotiations were not remotely likely at the time. Adams complied at first; but as time passed, he grew impatient. In July, he reopened the issue, writing a series of lengthy letters to Vergennes in support of his proposition, while also advising the French court on how its navy might better support the American cause.³⁴

Adams was well intentioned. Yet he was also heedless of European protocol and the broader political, military, and financial context in which Vergennes was operating. In late July, Vergennes sent Adams a point-by-point rebuttal, educating him on basic elements of European diplomacy. A treaty of commerce, he wrote, “must be founded on confidence and a union equivalent to an alliance… [and] can only be made between independent nations. To propose such a treaty in the midst of war, and at a time when England showed not the least inclination to recognize American independence, would convey weakness and desperation.” Moreover, it would also lend “credit to the opinion, which all Europe entertains… that the United States incline towards a defection [from France.]” When Adams still persisted in his position, Vergennes cut off their correspondence and instructed his minister in Philadelphia to put Congress “in a position to judge whether Mr. Adams is endowed with a character that renders him appropriate to the important task with which Congress has charged him.”³⁵

The dispute was not strictly legal in nature, yet it was related to the law of nations insofar as that law was embedded in a set of socialized standards of statehood. As David Golove and Daniel Hulsebosch have noted, there was a performative aspect to early modern statecraft in that ministers of state worked incessantly to uphold the honor and dignity of their sovereign and of the state that they represented. The ceremonial conventions of early modern diplomacy contributed to that end, while also stabilizing an otherwise treacherous environment by demonstrating the participants' willingness and capacity to follow the established rules. By displaying his inability, or disinclination, to follow such norms, Adams not only undermined Vergennes's confidence in his reliability, he also fueled perceptions that the United States did not yet merit the status of an independent state.³⁶

The most consequential effect of Adams's conduct was that it prompted Congress to place the negotiation of peace under the control of the French court. In the spring of 1781, Congress appointed four new peace commissioners to serve alongside Adams. The new commissioners were Benjamin Franklin, John Jay, Henry Laurens, and Thomas Jefferson—though Jefferson declined to serve. More significantly, Congress required all of the commissioners to submit to the advice and consent of the French court when negotiating peace with Great Britain. As the instructions put it, you are to “make the most candid and confidential communications upon all subjects to the ministers of our generous ally, the King of France; to undertake nothing in the negociations for peace or truce without their knowledge and concurrence; and ultimately to govern yourselves by their advice and opinion.”³⁷

The instructions represented a major abrogation of American sovereignty, and the United States’ interests might have suffered during the negotiation of peace if the effects of those orders were not subsequently mitigated by John Jay. At the outset of the war, Jay had no more experience with European diplomacy than his peers; yet during his first 2 years in Europe, from 1780 to 1782, he had endured perhaps the most difficult American negotiation of the war. While Jay was en route to Spain, Congress had undermined his mission by drawing funds on his account prematurely, in anticipation of his having secured a loan or subsidy from the Spanish court. The resulting debts gave Spain leverage in the ensuing negotiations over the Mississippi, and it was only with much tenacity and finesse that Jay left Spain, two years later, with the debts paid, and American claims to the Mississippi intact.³⁸

Jay's experience in Spain gave him unusual insight into the way that Europeans used customary law and rhetoric in pursuit of strategic interests. Because of that experience, and perhaps also because of his temperament, Jay took a different approach to diplomacy than Adams had in France. He was at pains to adhere to European protocol, yet also intensely jealous of the United States’ prerogatives as a sovereign state. The latter disposition became evident in Jay's reaction to Congress's aforementioned instructions to the commissioners of peace. While Adams and Franklin accepted Congress's orders without question, Jay protested them, going so far as to ask that Congress rescind his commission. He found it difficult, he wrote, to “reconcile myself to the idea of the Sovereign Independent States of America submitting in the persons of their Ministers to be absolutely governed by the Advice and Opinions of the Servants of another Sovereign, especially in a case of such national importance.” He asked that Congress, “take an early opportunity of relieving me from [this] station.”³⁹

Congress did not act on Jay's request and so his commission was still in effect when Franklin wrote, in the spring of 1782, to ask that Jay come to Paris and assist with the negotiation of peace—Adams being occupied at the time in the Netherlands. On arrival, Jay took a leading role in three decisions that nullified Congress's orders and established American control over the negotiations. The first decision came in July, when the British cabinet sent letters of authorization to one of its emissaries in Paris, empowering him to begin peace negotiations with, “the Colonies or Plantations of New Hampshire, Massachusetts…,” rather than with “the United States of America.” Vergennes advised the Americans to accept the document as written, arguing that “names signified little” in European diplomacy. Franklin would have accepted that advice, but Jay refused, insisting that the British treat with the United States as a sovereign state.⁴⁰

Jay's stance mattered, for the exchange of diplomatic credentials in Europe not only certified the statehood of the respective parties, but also implicated the honor of the respective sovereigns, thereby putting the negotiations on the record. If the Americans had accepted the British credentials as written, they would have admitted the “shameful mark of Subordination” to which Gérard alluded in his earlier advice to Congress. Moreover, the pending negotiations with Great Britain would have been illegitimate and subject to repudiation. Had the tide of war shifted in Britain's favor, George III could have rescinded any offers made by that point without loss of honor. The risk mattered little to Vergennes, who was committed principally to the cause of American independence, but it was important to the Americans who had other issues to resolve with Great Britain—including the western borders of the United States.⁴¹

In August, Jay used a similar dispute over diplomatic credentials to evade Spanish and French pressure to compromise on the Mississippi border. When Jay left Spain in May, the Spanish Prime Minister had instructed his ambassador to France, the Conde de Aranda, to continue negotiations with Jay in Paris. Floridablanca did not, however, provide Aranda with official letters of authorization, as he was not yet willing to acknowledge American statehood. In early August, Aranda held an informal conference with Jay, during which the two men discussed the western border of the United States. Jay claimed the Mississippi while Aranda proposed a line east of the river. Near the end of the conference, Jay presented Aranda with a copy of his credentials, but found that Aranda did not reciprocate.⁴²

Shortly thereafter, Jay met with Vergennes's secretary, Rayneval, who indicated that the French court supported Aranda's proposal for a border east of the Mississippi. Perceiving the weakness of his position, Jay moved to end the negotiations, pointing to Aranda's lack of credentials as a basis for doing so. When Rayneval argued that Jay should proceed on the basis of Aranda's character as a Spanish nobleman, Jay responded that to negotiate on that ground would leave Spain, “at liberty to disavow all his proceedings in such business.” When Aranda noted that Jay had already commenced negotiations with the Spanish Prime Minister in Madrid, without an exchange of credentials, Jay responded simply but correctly that the Prime Minister had been authorized ex officio to negotiate, such that an exchange of credentials was not needed in that case. On that basis, the negotiations came to close.⁴³

Jay made his third decision in September, shortly after learning that Rayneval had departed suddenly for England. Fearing that Rayneval had been sent to undermine Jay's position on both the British letters of authorization and the Mississippi border, Jay sent his own secret emissary to London, instructing him (1) to inform the British cabinet that peace negotiations with the United States would never begin without a valid exchange of diplomatic credentials, (by which Britain would have to concede the issue of American independence); (2) to argue that it was in Britain's interest to take that step decisively, so as to promote confidence between the two nations; and (3) to advance arguments in favor of an American border on the Mississippi and other related issues. As an added inducement, Jay instructed his emissary to assure the British cabinet that the United States would not submit to French interpretations of its obligations vis-à-vis the Franco–American treaty of alliance.⁴⁴

Jay's final point was made necessary by Articles II and VIII of the Franco–American treaty of alliance, in which the parties had agreed that “the essential and direct End” of the alliance was “to maintain effectually, the liberty, Sovereignty, and independence” of the United States; and that “Neither of the two Parties shall conclude either Truce or Peace with Great Britain, without the formal consent of the other first obtain'd.” Vergennes's policy, in the fall of 1782, was to delay British acknowledgment of American independence in order to keep the United States in the war, thus giving Spain time to achieve a separate set of territorial objectives. In that context, Jay was assuring the British cabinet that the Americans would decide for themselves whether France had grounds for withholding its consent to peace under the terms of Article VIII, if the United States received an acknowledgment of their independence from Great Britain that fulfilled the terms of Article II.⁴⁵

The British cabinet yielded to Jay's suggestion and empowered their emissary in Paris to negotiate with the “United States of America”—the first time that George III had used that title in official correspondence. The negotiations began in early October. By the end of November, the two parties had agreed to terms of peace that were widely regarded as favorable to the United States, including a western border on the Mississippi River. Jay's conduct was regarded by some Americans as a betrayal of France, yet he did not violate the terms of the alliance, nor did the United States drop out of the war prematurely. The Anglo–American agreement was preliminary in nature, and contingent on France reaching its own terms of peace with Britain, which it did shortly thereafter. In the definitive treaties that were signed the following year, France achieved nearly all of its strategic objectives for the war.⁴⁶

The essence of Jay's posture toward the customary laws of diplomacy was expressed in a draft letter to Vergennes, that he wrote in September 1782 but never sent. “When the United States became one of the Nations of the Earth,” Jay wrote, “they publish^d the Stile or name by which they were to be known & called, and as on the one Hand they became subject to the Law of Nations, so on the other they have a Right to claim and enjoy its Protection & all the Priviledges it affords.” The rights and privileges that Jay claimed in these negotiations were so commonplace in Europe as to scarcely merit attention. In the context of a war for independence, they took on much greater importance, giving us a chance to witness the role of customary law in early modern statecraft, and to appreciate Jay's status as perhaps the only American of his generation to use that law effectively in the diplomatic realm.⁴⁷