The best way to understand Polk's accomplishments in diplomacy and war is to study their development, step by step. On taking office, he inherited two major problems of foreign policy, both concerning American territorial expansion. At Tyler's urging, Congress had just passed a joint resolution authorizing annexation of the independent Republic of Texas. Most Texans wanted this, but their government hesitated. Meanwhile, agents of Britain and France urged Texas to remain independent, in order to offset the United States and create a balance of power in North America. Mexico, which still claimed sovereignty over Texas, threatened the United States with war if it went through with annexation and broke relations as soon as Congress passed the joint resolution.
An older controversy with Britain had been smoldering for years on the northwestern frontier. Both Britain and the United States claimed Oregon, a region west of the Rockies stretching from the northern boundary of California to the Alaska pan-handle (54°40') and including modern Oregon, Washington, and British Columbia. The conventions of 1818 and 1827 had established joint occupancy of this area, with provision for termination by either party after a year's notice. The Hudson's Bay Company dominated most of Oregon, but along the Columbia River, where fur trapping had greatly declined, American immigrants were establishing a chain of farming settlements, the vanguard of a great frontier movement. Tyler's secretary of state, John C. Calhoun, had opened exploratory negotiations over Oregon, but seeing the progress of American migration, he favored what he called "masterly inactivity" and soon let the negotiations lapse. Meanwhile, the British foreign secretary, the earl of Aberdeen, had come to the conclusion that the best solution to the question would be a compromise boundary along the forty-ninth parallel, reserving all of Vancouver Island to Britain, but he had not convinced the rest of the British cabinet, nor did he know how to suggest the compromise to the United States without weakening Britain's negotiating position.
The American desire for Upper California was also certain to affect Polk's foreign relations. California was undeniably Mexican territory, but distance and Mexico's political instability had allowed the province to drift away from Mexican control. The Californians were a mixture of Mexicans, Indians, Europeans, and Americans. New England traders had established firm economic connections between California's Pacific ports and the east coast of the United States. American explorers had traversed the interior, and early in the 1840s a few of the American emigrants to Oregon began to stray off into central California to take up farming or ranching. By 1845 the Mexican hold on California had virtually disappeared, and many Americans were wondering whether the British would intervene there as they were trying to do in Texas.
When Polk wrote his inaugural address, draft by draft, consulting many advisers as was his custom, he determined to deal explicitly with Texas and Oregon, leaving California for later disposition. He devoted considerable space to Texas, taking annexation for granted and warning foreign powers not to interfere in this purely American problem. He might have passed over Oregon with the remark that delicate negotiations were still pending, but the Democratic platform of 1844 had mentioned the "clear and unquestionable" American title to the whole territory, and this claim had aroused much enthusiasm in the Middle West during the campaign. Polk quoted this categorical phrase in his address without explaining his reference and went on to indicate that the United States government would protect the American emigrants to Oregon with laws and "the benefits of our republican institutions," looking toward annexation in the near future. Undoubtedly he hoped to satisfy the westerners without unduly arousing the British, but in the long run he was disappointed on both counts.
After his inauguration, the new president set out to complete the annexation of Texas. Thinking to secure Mexican acquiescence, he sent an unofficial diplomatic agent to reopen formal relations, hinting at a possible indemnity for Texas. He also sent agents to Texas to join the American chargé d'affaires, Andrew Jackson Donelson (Jackson's nephew and Polk's personal friend), in urging the Texas government to accept the terms of the joint resolution. British and French diplomatic agents were also working for reconciliation between Texas and Mexico. The British agent even persuaded the Mexican government to recognize Texan independence as an inducement to refuse annexation, but he was too late. By May, Texas public opinion was overwhelmingly annexationist, and in the following months the Texas Congress accepted the joint resolution, and a special constitutional convention drew up a new state constitution for membership in the Union.
Polk's success in Texas drew the United States closer to war with Mexico. On rather dubious grounds Texas claimed the Rio Grande as its boundary with Mexico, and without examining this claim carefully, Polk committed himself to its support. Mexican leaders denounced both the annexation and the boundary claim and threatened to attack the Texas frontier. Having promised to protect the Texans as soon as they accepted annexation, Polk dispatched a naval squadron along the Gulf coast and moved several thousand troops under Zachary Taylor from the Louisiana border to Corpus Christi on the Nueces River, at the northern edge of the disputed boundary zone, with permission to move south if Taylor thought best—a typical Polkian move to share responsibility but a reasonable one, considering the slowness of communications. At the same time, Polk sent private orders to Commodore John D. Sloat, commander of the Pacific squadron, that in case of war, Sloat should seize the principal ports of California.
Some historians believe that at this point Polk was consciously plotting war with Mexico. They rely on the private papers of Commodore Robert F. Stockton, the commander of the squadron protecting the Texas coast and an ultraexpansionist with powerful friends in the government. From certain inconclusive letters of his, it appears that he considered a preventive seizure of Mexican territory south of the Rio Grande. Also, according to President Anson Jones of Texas, Stockton proposed to him that the two of them provoke a war. Without written orders from Polk or some other equally clear evidence, the "plot thesis" rests on surmise. Instructions from Bancroft to Stockton and from Buchanan to Donelson were explicitly defensive, and Polk's correspondence and other factors suggest that at this time he neither desired nor expected war with Mexico.
Perhaps the best reason why Polk should have wanted to keep peace on the border was that Anglo-American relations had taken a turn for the worse during April and May because of the blunt passage on Oregon in his inaugural address. British observers failed to notice that the president had carefully respected the sanctity of treaties and that he was only following the example of the British government and the Hudson's Bay Company in proposing to extend legal protection to American settlers. Instead, the British press focused on Polk's assertion of the "clear and unquestionable" American title and hurled insults and threats at the overbearing Americans. When questions arose in Parliament, the prime minister, Sir Robert Peel, declared that Britain also had clear and unquestionable rights in Oregon. Naturally the American press seized all these statements and returned them with interest.
Behind the scenes the British government began unobtrusively to check Canadian fortifications—as well as Channel defenses, in case France supported the Americans. At the same time, Aberdeen encouraged a few moderates to disparage the value of Oregon in the press and sent instructions to the British minister at Washington, Richard Pakenham, to seek American terms or suggest arbitration of the Oregon question. Privately he encouraged Pakenham to draw from the Americans, if possible, an offer of the forty-ninth parallel and Vancouver Island, with the right to navigate the Columbia River, so that he might propose a compromise to the cabinet in London. Buchanan discouraged Pakenham's talk of arbitration but delayed further reply for several weeks.
At this point both parties blundered. When Buchanan gave Pakenham a formal reply on 12 July he indeed proposed the forty-ninth parallel, conceding to Britain all of Vancouver Island. Even though he made no reference to navigation of the Columbia River, these terms provided an adequate basis for negotiations. Unfortunately (and certainly on Polk's instructions) Buchanan set forth the ramshackle American claim to the whole area up to 54°40' in a manner that made the compromise offer seem an American condescension. Outraged, Pakenham replied with an equally strong statement of the British claim and, carried away by his own rhetoric, rejected Buchanan's offer out of hand instead of referring it to London, as he should have done. Apparently Polk then jumped to the conclusion that the wily British had tricked him into showing his cards without ever intending to compromise. After brooding for several weeks, at the end of August he had Buchanan withdraw the offer altogether and intimated that if the British wished to negotiate, they must assume the initiative with an offer of their own.
Thus, in the first six months of his administration, Polk had widened the breach with Mexico and Britain and limited his freedom of action in both cases. With a little more understanding of diplomacy, he might have managed to put Britain on the defensive without interrupting communications, by giving Aberdeen a chance to explain and excuse his minister's mistake. The situation called for Talleyrand's probing pen; instead, Polk had used an eraser. Since neither party would reopen negotiations for fear of losing face and bargaining leverage, the impasse over Oregon continued through the rest of 1845. When western expansionists learned of Polk's stand, they assumed that he would now carry out the Democratic party plank of pushing the boundary up to 54°40'. As he soon learned, such aroused expectations made any sort of compromise all the more difficult.
Still, the Mexican issue, at least, did not seem beyond peaceful settlement, for Polk's special agent to Mexico City and the American consul there reported throughout the summer that despite public fury at the American annexation of Texas, the government hesitated to start hostilities because of lack of funds and uncertainty about the loyalty of the army. Both thought that the government would receive a special American commissioner to discuss the Texas question (and presumably offer Mexico a disguised indemnity for its loss). It is not clear whether Polk understood the limited nature of the Mexican concession, but, true to his aggressive instincts, he determined to appoint a full minister plenipotentiary; ignore the Texas question, which he regarded as settled; and try to persuade Mexico to sell California. For this mission he chose John Slidell of Louisiana, a rising young politician with some polish and knowledge of Spanish but no previous association with Mexican affairs.
Before Slidell departed from New Orleans in late November 1845, news from the Pacific coast suggested that the California question might require more direct action. In mid-October, Buchanan received an alarming dispatch from Thomas O. Larkin, an American merchant-consul at Monterey. Larkin warned that Britain was apparently preparing to dominate California, for a new British vice-consulate had just been established at Monterey, probably to operate in conjunction with the Hudson's Bay Company; furthermore, there were rumors that Mexico was sending out troops, paid for by British money, to reassert authority. Larkin's report, three months old, was exaggerated or downright wrong, for the Hudson's Bay Company had lost interest in California trapping, the Mexican reinforcement expedition had been given up, and the British government, though deploring American influence there, was not disposed to take action. Polk and Buchanan, of course, had no way of knowing this.
The alarmed president determined to reinforce the Slidell mission with preventive measures in California. He drew up instructions for Sloat, repeating with emphasis that he should seize the principal Mexican ports in case of war. Polk also instructed Larkin to propagandize among the Californians for union with the United States and resistance to a British protectorate. These instructions Polk sent out with Commodore Stockton in the frigate Congress , but since that ship would need several months for the long voyage around Cape Horn, Polk selected a young marine lieutenant, Archibald H. Gillespie—apparently for no other reason than that he spoke Spanish. Polk gave Gillespie duplicates of the orders to Sloat and Larkin and told him to memorize the latter. Gillespie was to follow an overland route to California through central Mexico disguised as a merchant. At this point, Senator Thomas Hart Benton suggested that Gillespie should also carry coded orders and private letters to Benton's son-in-law, the army explorer Lieutenant John Charles Frémont, then conducting a reconnaissance in eastern California. Historians have long argued as to just what was in these orders, but unless their text is found (which now seems unlikely), no one can say definitively whether Frémont's later actions were authorized.
While Polk stood his ground on Oregon and California, he was also composing his first annual message to Congress, one of the most important documents of his whole career. In that message he said nothing of his hopes and plans for California but described the measures he had taken to protect Texas against Mexican aggression, outlined other grievances against Mexico, and characterized the Sli-dell mission as an effort to collect justifiable claims. Concerning Oregon, he summarized Tyler's negotiations and blamed Britain for their rupture. He called on Congress to provide an armed guard and land grants for emigrants to Oregon. First, however, in order to comply with treaty requirements, he recommended that Congress take steps to give the prescribed year's notice to terminate joint occupation.
After his discussion of Oregon, Polk reaffirmed "the principle avowed by Mr. Monroe"—the first significant presidential reference to the Monroe Doctrine since its original declaration in 1823. This passage has an interesting history. The president included something like it in an early draft of his inaugural address but soon deleted it. During the summer he was much irritated to read a statement by the French prime minister, François Guizot, that France must play an active role in North American affairs in order to maintain "l'équilibre des forces," which the American press translated as "the balance of power," a term embodying to Americans all the decadent, deceitful ways of monarchical Europe. After consulting Senator Benton and getting trial drafts from Buchanan and Bancroft, Polk drew up a statement.
In applying the Monroe Doctrine to Guizot's remarks, Polk was broadening it to include European political intrigue, as well as military action, in the New World, but at the same time, he implied a limitation by suggesting that the nature of the United States action under the doctrine might depend on the circumstances—a hint that Washington would be most concerned about violations near at hand. Guizot had been referring to Texas, for France had little interest in California and none in Oregon, but Polk intended his declaration to reinforce his analysis of the Oregon question and probably also to warn Britain off California.
Polk's annual message was an integral part of his aggressive strategy against Mexico and Britain. By justifying his policies, he sought to demonstrate that he was trying to preserve the peace, whatever the adversaries might do in the future. In the case of Oregon, he called on Congress for prompt, decisive action that would show government and country to be united behind him. Britain, he hoped, would then have to break the impasse at a disadvantage and offer new terms, which he could treat as he chose. What he really accomplished was to limit his actions further by revealing too much of his ambitions to the Mexicans and by making Congress his partner in determining policy toward Britain.
Under the political circumstances of the day it was unrealistic to expect prompt, decisive action from Congress. After the bitterly fought election of 1844, a Whig minority sought revenge and recovery of power. During the last phases of the Texas question, expansionism had become entangled with the antislavery cause; and the resulting confusion of personal ambitions, partisan loyalties, and ideological convictions made it impossible to predict anyone's actions. Rebellious factions threatened to split the Democratic party, especially a group of western expansionists—who now spread a newly coined slogan, "Fifty-four Forty or Fight!"—and a southern bloc led by Calhoun, who had put his whole heart into the campaign for Texas but now favored delay and compromise in Oregon.
The debate dragged on from December 1845 until late April 1846. As everyone realized, abrogation of the joint-occupation agreement would remove the only legal safeguard against war over some trivial local incident in Oregon. Polk wanted a simple, noncommittal statement advising the president to give notice of abrogation; western Democrats, especially in the Senate, wanted to add a shout of rude defiance that would effectively prevent any diplomatic response from Britain; and moderates at first opposed any notice at all. By February, Whigs and antiwar Democrats in the House of Representatives managed to pass a mildly worded resolution of notice that virtually invited Britain to resume negotiations but shifted full responsibility for them to the president. In April, after weeks of thunderous debate that stirred the country to its depths, the Senate finally accepted the House resolution, as Calhoun and his bloc recognized that some sort of notice was necessary. The innocuous wording infuriated western extremists, who foresaw a compromise settlement and suspected (probably with reason) that Polk had encouraged the moderates in the last weeks of the debate rather than have the Senate adjourn without acting.
As long as Congress wrangled, Polk could make no progress in negotiations with Britain during the winter of 1845–1846. Aberdeen was well aware of conciliatory sentiment in the United States through editorials and correspondence of eastern moderates, but he probably underestimated the force of western expansionism pressing on Polk. At first he hoped that Polk might change his mind and offer terms or agree to arbitration, but eventually he reconciled himself to waiting until Congress passed a resolution that would enable Britain to reopen negotiations without loss of face. Meanwhile, he dropped hints that Britain might send naval reinforcements to Canada if pressed too hard. (These hints undoubtedly helped induce Polk to favor compromise in the Senate.) Anglo-American diplomatic communications during the impasse were admirably maintained by the two ministers, Louis McLane in London and Richard Pakenham in Washington, who made as much sense as anyone could out of the complex situation.
At the same time, American relations with Mexico were also worsening. In early December, Slidell arrived in Mexico City, where he found nationalists livid at the idea of selling more territory and a moderate government clinging feebly to power. The foreign minister, unhappy at Slidell's inopportune arrival, refused to receive him, on the grounds that his credentials were those of a full minister plenipotentiary rather than a temporary commissioner. (This distinction was not mere desperate hairsplitting, as Polk thought, for if Mexico agreed to renew formal relations before negotiating, it would have little prospect of obtaining an indemnity or other concession in return for the loss of Texas.) At the end of the month, the nationalists staged a successful revolution and placed a conservative army leader, General Mariano Paredes y Arrillaga, in the presidential chair.
Since Paredes hoped for an Anglo-American war over Oregon, he too refused to receive Slidell. Undismayed at this setback, Polk advanced his position and took another strong stand. He ordered Taylor at Corpus Christi to move his forces across the disputed zone and occupy the north bank of the Rio Grande, avoiding any offensive action against the Mexicans. At the end of January he wrote to Slidell that if Paredes would not see him, "nothing can remain but to take the redress of the injuries to our citizens and the insults to our Government into our own hands."
Some historians have interpreted the strong language to mean that Polk never expected Slidell to succeed but intended the mission merely as an excuse for military attack. At the same time, Polk wrote to his brother that Paredes had probably exaggerated his anti-Americanism in order to gain power and that the order to Taylor was merely "a precautionary measure." Given the uncertain state of the Oregon debate at this time, it is reasonable to suppose that Polk hoped Slidell would sign a treaty but was prepared to increase the pressure if he did not. Nevertheless, his action in risking a Mexican attack might be criticized as compromising the powers of Congress.
During March and April 1846, Polk's relations with both Britain and Mexico reached a turning point. In Texas, Taylor led his army to the bank of the Rio Grande, where the soldiers built a fort within cannon shot of the Mexican border city Matamoros. In Mexico City, Slidell, following instructions, sent a final request for reception, received another refusal, and prepared to leave for home. In London the British government awaited action in Congress on the Oregon question, and in Washington the congressional debate was splitting the Democratic party and threatening Polk's whole legislative program. At the beginning of May, Polk was driven to the expedient of telling the Speaker of the House that if Congress tried to adjourn prematurely, he would forbid the action and force a showdown.
Hitherto, Polk had regarded war with Mexico as possible but unlikely. At some time during April 1846 he seems to have concluded that a short, limited conflict on the Rio Grande might be the best way to reunite his party, impress Britain, and bring Mexico to terms. Learning of Slidell's final rejection, he went over the whole matter with the cabinet, which agreed that he should send a message to Congress recommending that the United States take matters into its own hands. Polk kept delaying action, first waiting for the end of the Oregon debate, then for Slidell's return to Washington, and finally for some sort of Mexican attack that would arouse congressional patriotism.
The crisis came during the weekend beginning 8 May. On Friday morning Slidell arrived in Washington. After talking with him, Polk decided to make his appeal to Congress, but on Saturday morning he and the cabinet decided to wait a few days longer, hoping for further news from the Rio Grande. Four hours later, the adjutant general called at the White House with a dispatch in which Taylor reported that Mexican troops had ambushed one of his scouting parties north of the river, killing or capturing most of its members. Taylor remarked laconically, "Hostilities may now be considered as commenced." Polk agreed and spent most of Sunday composing a war message, which he sent to Congress next day. In this he discoursed on the "fair and equitable" principles the United States had displayed toward Mexico, recited American grievances, and justified Taylor's presence on the Rio Grande. Declaring that Mexico had "shed American blood upon the American soil," he called on Congress to ratify the fact that "war exists . . . by the act of Mexico herself."
Congress received this call to arms with mixed feelings. Nearly everyone recognized the danger to Taylor's men and favored voting reinforcements and supplies, but the Whigs and Calhoun's bloc of Democrats opposed a formal declaration of war or any statement blaming hostilities on Mexico until they could investigate the circumstances leading to bloodshed. Polk's supporters outmaneuvered them at every point, while the president himself pressured Benton, a key figure, to swallow his doubts. The war bill was passed by an impressive margin, but Whigs voted for it unwillingly, lest their party suffer the stigma of disloyalty and go to pieces as the Federalist party had done during the War of 1812.