Franklin Pierce’s eventual victory left the Whigs and the Free-Soilers in disarray. A third of southern Whigs threw their support to the Democrats, seeking a truly proslavery party. Many Democrats who had supported Free-Soilers in 1848, like Martin Van Buren, were driven to vote for Pierce by their enthusiasm over the admission of California as a free state. But despite the Democratic triumph, that party also remained fragile. The nation now faced some of its gravest challenges under a president with limited political experience and no firm base of support. His cabinet included men of widely differing views, part of an effort to appease the various factions of the Democratic Party. But when confronted with difficult decisions, Pierce often received contradictory advice and generally pursued his own expansionist vision.

Early in his administration, Pierce focused on expanding U.S. trade and extending the “civilizing” power of U.S. institutions to other parts of the world. Inspired by the promise of new markets, Pierce and his supporters sought to shift Americans’ attention outward. Trade with China had declined in the 1840s, but the United States had begun commercial negotiations with Japan in 1846. These came to fruition in 1854, when U.S. emissary Commodore Matthew C. Perry obtained the first formal treaty with Japan that allowed for mutual trading. Within four years, Pierce and his agent, international trader Townsend Harris, succeeded in expanding commercial ties and enhancing diplomatic relations with Japan, in large part by ensuring U.S. support for the island nation against its traditional enemies in China, Russia, and Europe.

Although the president rejected Commodore Perry’s offer to take military possession of Formosa and other territories near Japan, Pierce was willing to consider conquests in the Caribbean and Central America. For decades, U.S. politicians, particularly Southerners, had looked to gain control of Cuba, Mexico, and Nicaragua. A “Young America” movement within the Democratic Party imagined manifest destiny reaching southward as well as westward. In hopes of stirring up rebellious Cubans against Spanish rule, some Democrats joined with private adventurers to send three expeditions, known as filibusters, to invade Cuba under the leadership of Cuban exile General Narciso Lopez. In 1854 the capture of one of the filibustering ships led to an international incident. Spanish officials confiscated the ship, while Democrats eager to add Cuba to the United States urged Pierce to seek an apology and redress from Spain. But many northern Democrats rejected any effort to obtain another slave state, and Pierce was forced to withdraw even tacit federal approval for the filibusters.

Other politicians still pressured Spain to sell Cuba to the United States. These included Pierce’s secretary of state, William Marcy, and the U.S. ambassador to Great Britain, James Buchanan, as well as the ministers to France and Spain. In October 1854, these ministers met in Ostend, Belgium, and sent a letter to Pierce: “If we possess the power, [the United States is justified] by every law, human and Divine” in taking Cuba by force. When this Ostend Manifesto was leaked to the press, Northerners were outraged. They viewed the whole episode as “a dirty plot” to gain more slave territory and forced Pierce to give up any plans to obtain Cuba. In 1855 a private adventurer named William Walker, who had organized four filibusters to Nicaragua, invaded that country and set himself up as ruler. He then invited southern planters to take up vast lands he had confiscated from local farmers and to reintroduce slavery in Nicaragua. Pierce and many Democrats endorsed his plan, but neighboring Hondurans forced Walker from power in 1857 and executed him by firing squad three years later. Although Pierce’s expansionist dreams failed, his efforts heightened sectional tensions.