The European discovery of Cuba took place on October 12, 1492, during the Christopher Columbus's first voyage of discovery. It became an important colony of Spain. One of the factors that may have led to the Monroe Doctrine in 1823 was American fears that the weak Spanish control of Cuba would pass to more vigorous colonial powers like France or Britain. In 1848, President James K. Polk offered to purchase Cuba from Spain for $100 million, but Spain declined. An expedition under the leadership of General Narciso Lopez attempted to seize Cuba from Spain by force in 1849, but failed. Another attempt, supported by Southerners who hoped to make Cuba another slave state in the Union, was put together in New Orleans in 1850 but again failed. A third invasion the following year again failed. In 1854, Secretary of State William Marcy authorized three Americans -- the future president James Buchanan among them -- to investigate the feasibility of purchasing Cuba from Spain. The three exceeded their authority when they drafted and released a document, known as the Ostend Manifesto, which suggested that Spain could either sell or lose Cuba to force. The document was repudiated by President Franklin Pierce, there being no international support and no domestic support outside the South. Cuba gained its independence from Spain during the Spanish-American War of 1898. Its national policies remained under American supervision for another three decades, however. After World War II, Cuba became a haven for American criminal elements, who operated openly in Havana. Fidel Castro overthrew the pro-American dictator Fulgencia Batista on New Years Day in 1959. He established a socialist government that has been in conflict with the United States government for more than half a century. The United States maintains an embargo which forbids trade with or travel to Cuba by Americans. The embargo is not supported by any other nation.