William Walker, a lawyer turned adventurer, became known for his role in various filibustering campaigns throughout Latin America. In 1855, he set his sights on Nicaragua, where political instability provided an opportunity for his ambitions. At the time, the country was embroiled in civil war, and Walker capitalized on the conflict by assembling a group of mercenaries to support a local faction. He landed on the Pacific coast of Nicaragua, quickly making his way to the city of Granada, which he captured with relative ease. His forces took control of the strategic city and he declared himself president, establishing a government that favored American interests, particularly those aligned with Southern slaveholders.

Walker's presidency was characterized by efforts to promote the introduction of slavery in Nicaragua, as he aimed to create a plantation economy reminiscent of the Southern United States. He sought to expand his influence and control over Central America, encouraging American settlers to migrate there. However, his rule was plagued by challenges, including ongoing resistance from local forces and dissatisfaction among his own troops. In response to growing unrest, Walker implemented harsh measures to maintain control, leading to a volatile environment that persisted throughout his administration.

Ultimately, in 1857, Walker faced opposition from a coalition of Nicaraguan forces and was forced to flee the country after a brief period of fluctuating support. His adventure had lasting implications for U.S.-Latin American relations and highlighted the contentious issues surrounding expansionism and slavery during this period. Walker's actions showcased the implications of filibustering and the American desire for territorial expansion in the 19th century, raising questions about the legitimacy and morality of such interventions in sovereign nations.