During the years after the compromise, the foreign relations of the United States were characterized by the same sense of national importance and spirit of expansion which brought about the annexation of Texas, the Oregon controversy, and the Mexican War. A feeling of "manifest destiny" was in the air; people looked for additions of territory to the southward and approved of a policy of national assertion at the expense of neighboring states and of European powers. 

It was an era of a crude belief in the universal superiority of "American institutions," a lofty contempt for the "effete monarchies" of Europe, and a strong sense of the righteousness of any aggressive action which the republic might undertake. Although the secretaries of state during this period were northern men of the older race of statesmen, Clayton, Webster, and Everett under Fillmore, Marcy under Pierce, and Cass under Buchanan; and were inclined by their political experience and their mature years towards a cautious policy, they could not avoid being influenced by the prevailing spirit and showing it in language and action.

The chief obstacle in the way of a vigorous foreign policy, expressing this spirit of "manifest destiny," was the strong dislike which had grown up in the northern states towards any annexation involving an increase of slave territory. This feeling was shared by conservatives and antislavery men alike, and its existence, although veiled in the era of political calm, was known to the statesmen in charge of foreign affairs and had a strong restraining influence. Not even Marcy, the boldest of them all, was inclined to take any radical action without unmistakable signs of northern acquiescence. Nevertheless, so complete was the sectional quiet during Fillmore's term and the first part of Pierce's, that for a time an aggressive policy seemed likely to succeed.

The defiant attitude of the democratic republic towards "European despotism" was illustrated by a series of contentions with Austria. In 1849, Clayton sent an emissary, Dudley A. Mann, with instructions to recognize the Hungarian Republic in case it appeared to be firmly established. He found Hungary prostrate and so took no action; but the purpose of his errand became known to the Austrian government, which instructed Huelsemann, the Austrian charge-J'affaires, to protest against the mission as unfriendly. It fell to Webster to respond, and he yielded so far to the complacency of the time as to write, December 1850, a spirited reply, denying that the visit was an unfriendly act, and asserting the right of the American people to sympathize with the efforts of any nation to acquire liberty. He concluded with a direct comparison between Austria and the United States: "The power of this republic," he said, "at the present moment is spread over a region one of the richest and most fertile on the globe, and of an extent in comparison with which the possessions of the House of Hapsburg are but a patch on the earth's surface. . . . Life, liberty, property, and personal rights are amply secured to all citizens and protected by just and stable laws; and credit, public and private, is as well established as in any government of continental Europe. . . . Certainly the United States may be pardoned, even by those who profess adherence to the principles of absolute governments, if they entertain an ardent affection for those popular forms of political organization which have so rapidly advanced their own prosperity and happiness, and enabled them in so short a period to bring their country and the hemisphere to which it belongs to the notice and respectful regard — not to say the admiration — of the civilized world."

Immediately following this letter, which Webster wrote, as he explained, in hopes of stimulating pride in the Union, the Kossuth craze came to emphasize the popular sympathy with republican aspirations, and the general detestation of Austria and Russia. In 1853 a similar opportunity was presented to Marcy, when Martin Koszta, a Hungarian refugee to the United States, who had declared his intention of becoming a citizen, returned to Europe before completing his naturalization and was seized by an Austrian cruiser in a Turkish port. Captain Ingraham, of the United States man-of-war St. Louis, took the bold step of forcing the Austrian vessel to release Koszta, and Huelsemann promptly presented a demand for reparation and the disavowal of his behavior; but Marcy, in a long despatch, absolutely refused any conciliatory action and justified Ingraham's course.

National scorn of monarchical customs was also amusingly exhibited by a circular, issued when Marcy took charge of the state department, which advised American representatives at foreign courts not to wear any ceremonial uniforms, but to appear "like Franklin, in the simple costume of an American citizen." The sensation produced at several European capitals by the appearance of American ministers in ordinary civilian clothes was as ludicrous as it was genuine; and in Prussia, Spain, and France they were practically compelled to invent a court dress. Mason, in Paris, chose a fancy costume concocted by a Dutch tailor after the model of the servants of the Austrian legation. Buchanan, at London, provoked sneers in Conservative newspapers and had some difficulties with the master of ceremonies, but was finally allowed to attend in the "ordinary dress of an American citizen," to which, in order to distinguish himself from the court servants, he thoughtfully added a small sword. By this episode, as by the Austrian correspondence, notice was served upon Europe of the independent, democratic standards of the American republic.

In diplomatic dealings involving positive action, the United States showed a vigorous attitude in minor matters in the far east. Under Webster and Marcy the Japanese government was obliged to receive the expedition of Commodore Perry in 1853, and to make a commercial treaty the next year, which opened Japanese ports to American trade and began the process of introducing western civilization. Marcy went so far as to attempt to annex Hawaii, a step from which Webster had recoiled, and his plan was only wrecked by the death of the Hawaiian king in 1854. Nearer home, a boundary question, arising over the line laid down in the treaty of Guadalupe-Hidalgo with Mexico, was settled in 1853 by purchasing, through James Gadsden, a strip of territory to the south of the Gila River, in order that a future Southern Pacific railroad might run wholly over United States soil.

In like manner, the long-standing quarrel between Canadian authorities and New England fishermen, over the privileges granted by the treaty of 1818, was settled in this period. The Canadian government was eager to purchase commercial reciprocity, using the fisheries as a make-weight; but no treaty could be obtained, although an emissary made a fruitless visit to Washington in 1851. After this failure, the Canadians resorted to the use of British men-of-war to seize suspected fishermen, which stirred up great indignation in New England, but led to no action until, in Marcy's regime, Lord Elgin visited Washington and succeeded in securing the ratification of a reciprocity treaty in 1854. This granted equal fishing rights (inshore and river fishing excepted) in return for commercial concessions. The kind of diplomacy used by Lord Elgin was described by Laurence Oliphant of his suite, as "chaffing Yankees and slapping them on the back." "If you have got to deal with hogs," he queried, "what are you to do?"

The really serious problems of these years, however, were those connected with southern expansion. The first related to Cuba, the annexation of which was ardently desired in the southern states, partly as an expression of the general spirit of expansion, but more from the desire for slave territory. "If we hold Cuba," wrote one enthusiast, "we will hold the destiny of the richest and most increased commerce that has ever dazzled the cupidity of man. And with that commerce we can control the power of the world. . . . The world will fall back upon African labor, governed and owned in some shape or form by the white man, as it always has been.. . . We, too, are in the hands of a superintending Providence to work out the real regeneration of mankind."

The other problem related to the control of the isthmus of Central America, which suddenly became important after 1848 as a link in the sea passage to California. In the case of each of these regions, the desires of the southern people were so keen that they led to repeated attempts by adventurers to gain military control in the hope of bringing about an eventual annexation. Whenever the government, impelled by popular interest, took any steps towards carrying out the expansionist dreams, it encountered the direct opposition of Great Britain in each field; and the diplomatic dealings which resulted were not confined to Spain or the petty Central American republics, but bore the character of a duel with a determined and persistent adversary and rival.

The first steps towards Cuban annexation in this period were taken under Polk, in 1848, when Saunders, the American representative at Madrid, was instructed to sound the Spanish government. The prompt reply he received from the minister of foreign affairs was typical of the Spanish attitude on the question from this time until the crisis half a century later. He was told that "it was more than any minister would dare to entertain such a proposition;. . . such was the feeling of the country that sooner than see the island transferred to any power they would prefer seeing it sunk in the ocean." In the face of such a determined position, no further action was taken by the United States, but the idea was spread in the south by Spanish refugees that Cuba itself was ready to revolt, resulting in a series of filibustering attempts, engineered by Narcisso Lopez, an adventurer from South America. Although the Spanish minister at Washington, the persistent Calderon de la Barca, was kept well informed of the progress of every plot and poured a stream of angry notes upon the state department, nothing could prevent the raiders from acting. Clayton and Webster were honestly desirous to preserve neutrality, but the sympathy of nine-tenths of the southern people was so strongly with Lopez that the laws could not be enforced. Taylor issued a proclamation against filibustering in 1849 and managed to prevent the departure of the first expedition, but the second one escaped, only to fail miserably, Lopez taking refuge at Key West, while a number of his followers were caught and tried for piracy.

Clayton used his utmost efforts to secure the release of these men, going so far as to threaten a "sanguinary war" in case the prisoners were not sent home to meet the merited punishment of "the indignant frowns of their fellow citizens," but it was not until Webster became secretary that their release was accomplished through Barringer, the minister at Madrid. Meanwhile, Lopez was triumphantly acquitted by a southern jury when tried on the charge of violating the neutrality laws, gathered a new force, undisturbed by Calderon's heated protests, and made a second descent on the island in August 1851. He found no support, was driven to the hills, captured, and promptly garroted; while fifty of his followers, including young men from prominent southern families, were shot after a summary court-martial. When the news of this severity reached New Orleans, the center of filibustering sympathy, a mob wrecked the Spanish consulate, defaced a portrait of the queen, and looted Spanish shops.

In this affair, the United States was so clearly in the wrong that aggressive action was out of the question. Webster offered reparation for the insult and recommended that Congress make indemnity for the damage, but although this straightforward action secured the release of the surviving prisoners, relations with Spain continued to be strained. The Cuban administration adopted a suspicious and arbitrary attitude towards Americans, and the last months of Fillmore's term were filled with complaints from traders of intolerable exactions and extortions for which no redress could be obtained since the Spanish captain-general had no diplomatic functions and declined to deal with American consuls or agents.

The unconciliatory attitude of the Spanish government at this time was undoubtedly due to a sense of British support. In 1851 the British and French ministers announced at Washington that their men-of-war had orders to prevent filibustering, which brought out from Crittenden, acting secretary during an illness of Webster, a strong protest. Later, in April 1852, at the suggestion of the Spanish government, England proposed a tripartite agreement, by which Great Britain, France, and the United States should mutually renounce any purpose of annexing Cuba; but Everett firmly declined to be drawn into any such arrangement, on the ground of the peculiar interests of the United States in the island.

When Pierce assumed office, the whole country undoubtedly looked for vigorous action in foreign affairs, especially the annexation of Cuba; and Marcy, his secretary, was expected to take the matter promptly in hand. Marcy, however, although not averse to annexation, was conservative, cold-blooded, and lawyer -like, and unwilling to take decisive steps without a perfectly secure footing. This caution fell far short of the desires of the southern Democrats and, for the moment, of the northern party leaders; for in 1853 the exasperation in commercial centers over the unfriendly Spanish policy in Cuba was such that a war might not have been unpopular. The new minister at Madrid was Pierre Soule, of Louisiana, a hot-headed Frenchman, an avowed annexationist, and a sympathizer with filibusters, a man contrasting strongly with his Whig predecessor, the firm yet cautious Barringer. Marcy's instructions to Soule bade him be slow to raise the question of annexation, in view of the existing irritation of Spanish feeling; but directed him to press for reparation for outrages in Cuba and especially to demand the conferring of sufficient diplomatic power upon the Cuban captain-general to permit complaints to be lodged with him without the necessity of waiting weeks and months for replies from Madrid.

Soule's career in Spain was a series of blunders. At the outset, finding no business of a pressing character, he vented his temper in a duel with the French ambassador. Soon news came from Cuba which seemed to the excitable minister the proper pretext for a diplomatic rupture. The cargo of the steamer Black Warrior, which for months had been making trips to Havana without molestation, was suddenly condemned for the violation of an obsolete harbor regulation, a crowning example of the irritating policy of the Cuban authorities. The hotheads in the United States clamored for war, and Congress resounded with angry speeches; but Soule, in his rashness, threw away whatever tactical advantages this situation had given him. After presenting a claim for damages on April 8, and receiving no reply for three days, he sent a second note demanding reparation within forty-eight hours, under threat of asking for his passports. Such hasty action transferred the grievance to the other side, now represented by the former minister to Washington, Calderon de la Barca; and since Soule was left without support from Marcy the whole affair evaporated in bluster. In spite of Soule's angry arguments that Spain needed to be taught a lesson, Marcy would make no ultimatum; for events at home had begun to appear so threatening that the secretary was resolved to invite no foreign complication. In 1855 the United States accepted a tardy apology and reparation for the Black Warrior seizure, and the incident was closed.

Meanwhile, Soule made a final false step, which led to the collapse of his diplomatic career. Marcy instructed him to join with Mason, minister to France, and Buchanan, minister to England, in conferring upon a policy to be followed by the United States towards Cuba, and the three ministers met accordingly, at Ostend, in the summer of 1854. The result was the draught of a manifesto which was sent to Marcy in October, to the effect that Spain ought to sell Cuba to the United States; that Cuba was necessary for the safety of slavery in the southern states of the Union; and that if Spain, "dead to the voice of her own interest and actuated by ... a false sense of honor, should refuse to sell Cuba," then, in case the internal peace of the Union was endangered, "by every law, human and divine, we shall be justified in wresting it from Spain if we possess the power." In transmitting this surprising document, Soule added that now was the time to declare war upon Spain, since England and France were involved in the Crimean struggle and would be unable to interpose.

Marcy, however, received the manifesto with ill-concealed surprise, and replied in a note which ironically assumed that "It was not intended by yourself or your colleagues to offer to Spain the alternative of cession or seizure." When the correspondence and the manifesto were published in March 1855, the unsparing condemnation expressed in the north showed that the time had gone by when an aggressive Cuban policy could receive support or acquiescence from a united public. Soule resigned in disgust and the Cuban episode came to an end.

The Central American question brought the United States into conflict with an equally pertinacious and more formidable antagonist. Great Britain was first in the field with the colony of Belize on the coast of Honduras and a traditional but ill-defined protectorate over the obscure tribe of Mosquito Indians on the eastern shore of Nicaragua. When the importance of the isthmian transit became visible, especially the Nicaragua route, a sudden scramble began for its control. Chatfield, the British representative, showed a tendency to stretch the elastic Mosquito protectorate over the San Juan River — the eastern part of the Nicaragua passage — and in 1849 caused the occupation of Tigre Island, on the coast of Honduras, to command the western end. Hise, the American minister sent by Polk, met this move by securing a treaty from Nicaragua which gave the United States exclusive privileges over the canal route; and when this failed of ratification by the Senate, Squier, his successor, made another treaty, securing somewhat less extensive privileges, and, in addition, induced Honduras to cede Tigre Island, which the British had occupied, to the United States.

Each country protested vigorously against the actions of the other's agents, but after a year of negotiations, Clayton agreed with Sir Henry Bulwer, in 1850, upon a treaty which compromised the rival claims. Each country promised to aid in the construction of an interoceanic canal through Nicaragua, to guarantee its neutrality, and explicitly to renounce any "dominion over Nicaragua, Costa Rica, the Mosquito Coast or any part of Central America." The principle of neutrality was to be extended to any other canal that might be built, and other powers were invited to join in the neutralization of the region. This arrangement was regarded at the time as a substantial triumph for the United States, and during the next two years, Webster labored vainly to settle the dispute between Nicaragua and Costa Rica, concerning their boundary in the vicinity of the San Juan River, where an American "Accessory Transit Company" was now operating a line of steamers.

As time went on, however, the conditions on the isthmus did not seem to square with the state of things assumed in the treaty. While Great Britain abandoned Tigre Island, she still retained the Mosquito protectorate as well as Belize; and in the summer of 1852 took the step of annexing some islands off the Honduras coast and erecting them into the colony of "The Bay Islands." At the same time Greytown, a trading post in Nicaragua at the mouth of the San Juan River, was established as a "free city" through the active support of the British representative in the so-called Mosquito protectorate. In 1851 this mushroom sovereignty endeavored to levy port dues upon the steamers of the Transit Company, and when one of these, the Prometheus, refused to pay, it was fired upon by a British man-of-war. These actions could not fail to create an impression in the United States that England was deliberately violating the Clayton - Bulwer treaty, and caused widespread indignation.

Finally, in the last session of Congress in Fillmore's term, it was brought to light in a heated debate in the Senate, that before signing the treaty in 1850, Sir Henry Bulwer had left with Clayton a memorandum stating that the British government did not construe its renunciation of "dominion" in Central America to apply to Belize "or any of its dependencies." This explained the recent action of England and made it clear that Clayton, in allowing this memorandum to stand as an unacknowledged part of the treaty, had deprived his work of much of its value. The whole subject was accordingly reopened.

When Marcy assumed office he took up the problem in a resolute fashion, making a direct attack upon the British position by instructing Buchanan to insist upon a renunciation by Great Britain of the shadowy Mosquito protectorate. Marcy's language was that of an aggrieved party and was so vigorous that Lord Clarendon termed it "hostile." He not only stigmatized the retention of the Bay Islands and the Mosquito claim as a violation of the treaty and a mere "convenience to sustain British pretensions," but denied any legal basis for the Belize Colony. To this Clarendon replied emphatically that the Clayton-Bulwer treaty was not meant to be renunciatory and would not be so construed by the British government. Meanwhile, to aggravate the situation, an explosion took place at the self-styled "free city" of Grey town. The Accessory Transit Company continued to be embroiled with the "City" government, its buildings being saved from destruction only by the interposition of the United States vessel the Cyane; until in June 1854, an affray occurred in which one of the officers of the company's steamers killed an individual, and a mob, in revenge, attacked the United States consul. Thereupon Lieutenant Hollins, of the Cyane, demanded reparation, and, in default, bombarded and destroyed the town; while the commander of a British vessel present at the time protested that only inferior strength prevented him from interposing. Each government seemed inclined to maintain its position stiffly, and the action of the United States showed a willingness to resort to force.

At this juncture, when the United States had embarked in a serious controversy with Great Britain, marked by every sign of ill-temper, and while Great Britain was embarrassed by the outbreak of the Crimean War, Marcy contented himself with furnishing arguments to Buchanan and hinting at the abrogation of the treaty, but took no definite action. The quarrel which had begun so threateningly dwindled to a mere diplomatic fencing between the patient and courteous Buchanan and the British foreign secretary, in such spare moments as the latter could afford in the midst of his serious European complications.

The influence which put a veto upon an aggressive policy towards Spain and restrained Marcy from pushing the Central American controversy with vigor was a sudden violent tempest of sectional feeling and an overwhelming defeat of the Pierce administration at the polls. The attention of the country was wholly engrossed with a renewal of the slavery controversy, and Marcy was far too prudent to commit the administration to any grave foreign policy in such a crisis. The time for southern expansion as a means for increasing slave territory had gone by.