Tyler's unfortunate relationship to Congress permitted him little scope for leadership in domestic matters, but he exploited his powers as president effectively in the realm of foreign affairs. Remarkably sensitive to America's strategic and economic opportunities, he was, unlike Clay or Van Buren, a vigorous expansionist. So energetic was he in promoting his policies that he was largely instrumental in shifting popular attention away from the public questions that had dominated the Jacksonian era, to new and ominous issues that were to come to a head in his successor's administration.
Of immediate concern as he assumed office were relations with England. Several explosive issues had combined to produce such tensions between the two nations that there was talk of war on both sides. In the wake of the ill-fated rebellions in Canada in 1837, there had been a series of nasty incidents along the border that resulted from raids by expatriate rebels and their American sympathizers. Other troubles erupted in 1839 with the Aroostook War, in which men from Maine clashed with those from New Brunswick in the disputed area between the two jurisdictions. Southern sentiment was aroused when, in November 1841, an American ship, the Creole , carrying slaves from Virginia to New Orleans, was taken into the Bahamas following a mutiny and the British refused to return the slaves to their owners.
Webster, as secretary of state, was eager to compose differences with England and had Tyler's full support and cooperation. With the arrival in the spring of 1842 of a special British emissary, Lord Ash-burton (Alexander Baring), amicable negotiations got under way, culminating in the Webster-Ashburton Treaty (August 1842). The most vexatious issue was the northern boundary of Maine, which had remained undetermined since the Treaty of Paris in 1783. Some twelve thousand square miles were in dispute. By clever but not entirely ethical means, Webster induced Maine and Massachusetts, of which Maine had formerly been a part, to yield to a compromise that gave five thousand square miles of the contested region to New Brunswick. Minor adjustments were made in the northern boundaries of New Hampshire, Vermont, and New York. Farther west, the British gave up sixty-five hundred square miles on the border between Lake Superior and the Lake of the Woods, where in 1887 the great Mesabi iron ore deposits were discovered. To reduce tensions between the two nations over efforts to suppress the slave trade, it was agreed that each would accord the other the "right of visit" when the ships of either nation were suspected of carrying slaves and that the United States would maintain a squadron in African waters to cooperate with the British fleet in preventing the traffic in slaves. In supplemental notes, the problem of the border incidents was resolved by an agreement on the mutual extradition of criminals. Although some disappointment was expressed that the negotiations had not resolved the status of Oregon, the treaty was speedily approved by the Senate, and what might have become a serious crisis was averted.
In a more remote sphere, the Tyler administration was successful in establishing treaty relations with China. Although Americans had long conducted a prosperous trade with that ancient nation, Britain's victory over China in the Opium War (1839–1842) seemed to promise even greater commercial possibilities there. Accordingly, Tyler dispatched Caleb Cushing of Massachusetts as a special commissioner to negotiate with imperial officials. His efforts—backed by four warships—resulted in the Treaty of Wanghia (1844), which secured for Americans the same trading privileges that had been extorted by the British. Tyler also manifested interest in Hawaii, then an independent kingdom that saw itself threatened by the intervention of foreign nations. Noting that most of the ships putting into port there were American and that numerous American missionaries had settled there, Tyler, in his annual message to Congress in December 1842, extended the principles of the Monroe Doctrine to Hawaii: the United States, he asserted, would view with "dissatisfaction" any attempt by another nation to take possession of Hawaii or subvert its government.
Closer to home, Tyler declared an end to the costly and inhumane war against the Seminole Indians. The last remaining Indian nation in the South after the others had been forcibly removed to reservations west of the Mississippi by Jackson, the Seminoles had been induced to sign a fraudulent treaty in 1833, giving up their remaining lands. Led by Chief Osceola, they had resisted and for nearly a decade had been harried by American troops until only a small remnant remained. At that point, Tyler announced the termination of hostilities in a message to Congress in May 1842.
Of far larger consequence was Tyler's interest in the vast territory that was known as Oregon. Located west of the Rocky Mountains and extending from the forty-second parallel (the present northern boundary of California) to 54°40' north latitude (the southern boundary of Alaska, then a Russian possession), Oregon was claimed jointly by the United States and Great Britain on the basis of early voyages of discovery. By the Convention of 1818, the two nations, unable to decide on a boundary between their claims, had agreed to joint occupation of the region. This agreement was extended indefinitely in 1827, with the provision that it could be terminated by either party upon giving one year's notice to the other. Prior to 1840 there had been negligible American settlement in the area. The British presence was represented by the Hudson's Bay Company, which maintained fur-trading posts in the Columbia River valley and elsewhere north of that river.
By the time of the Webster-Ashburton negotiations, the British were prepared to agree on a division of the territory with the Columbia River as the boundary, but this was unacceptable to the United States, for it was known that the entrance to that river was unsuitable as a harbor. Webster countered with a proposal that Britain persuade Mexico to cede to the United States part of California, including the excellent port of San Francisco, in return for which he would accept the Columbia as the Oregon boundary. When this gambit failed, the Oregon issue was left unresolved.
In the same year, popular interest in Oregon rose markedly as the result of the publication of glowing reports from the exploratory voyage of Lieutenant Charles Wilkes and accounts sent back by the first organized party of settlers to venture over the Oregon Trail. By 1843 hundreds of pioneers were heading for the Willamette Valley. In July 1843 delegates from six western states met in convention in Cincinnati and adopted resolutions asserting that the United States had valid title to all of Oregon and calling for the extension of American jurisdiction over the whole region. Similar pronouncements were soon being made by western spokesmen in Congress.
Tyler shared the rising expansionist sentiment. In December 1841 he had urged Congress to appropriate funds for a chain of forts from Council Bluffs, Iowa, to some point on the Pacific "within our limits" to protect the route of travel to Oregon. A year later he called attention to the Oregon question, indicating that he would press the British for a settlement. In his annual message in December 1843, he was explicit, if not entirely candid, in declaring that "the United States have always contended that their rights appertain to the entire region of country lying on the Pacific and embraced within 40° and 54°40' of north latitude." In actuality, he would have settled for a division along the forty-ninth parallel, including the magnificent harbor of the Juan de Fuca Strait. This was the boundary that was to be agreed on in 1846. But Tyler was not energetic in pressing for Oregon, because by 1843 his attention was focused on what he regarded as the grandest objective of his administration—the annexation of Texas.