This meaning of the word "filibuster" came first, and led to the more common use today of a Congressperson speaking nonstop to keep a bill from passing. One filibuster was named William Walker, an American who went to Nicaragua in 1855 with less than 100 fellow Americans and managed to seize control of the country!
At the time, the Panama Canal had not been built, and the only practical way for anyone to travel from the US East Coast to San Francisco was via steamships to Nicaragua or Panama, then a treacherous journey over land, rivers and lakes, then another steamship from the Pacific Coast up to San Francisco. Because gold was discovered at Sutter's Mill in California in 1848, starting the Gold Rush, many people undertook this arduous, multi-day journey. Cornelius Vanderbilt had designed and still controlled the Nicaragua route, while competitors controlled the Panama route.
The filibusters hoped to capture territory that would later be annexed into the United States, which would import laws, culture, and slavery. One filibuster movement wanted to invade and annex Cuba, which had slavery, in order to further expand the amount of US territory where slavery was practiced. This was the antebellum era of the Compromise of 1850, the Kansas-Nebraska Act, and the Fugitive Slave Act, all crafted as part of the struggle to prevent a Civil War over how much of the US would be slave territory.
As for William Walker seizing control of Nicaragua, he sent a "minister" to negotiate with the Franklin Pierce administration, which refused to recognize his legitimacy or allow US citizens to reinforce him. Walker then seized Vanderbilt's transit company in Nicaragua, Accessory Transit, and set to establish a new transit line through the country and from New York City to San Francisco. The Pierce Administration did nothing to protect Vanderbilt's property rights, in part because Secretary of War Jefferson Davis hoped Nicaragua would be annexed by the US as a slave territory! Nicaragua had banned slavery over three decades before, but Walker reimposed it. A few months later, Pierce recognized Walker's government to help his reelection chances with pro-slavery Democrats.
William Walker later faked an election, whereby instead of ruling through a puppet native Nicaraguan president, he had himself elected directly. Eventually Walker was forced to surrender by a combined force of Central American armies, who forced him to surrender to the US Navy, who dropped him in New York City, where he wrote an autobiography. Walker then returned to the region, was captured by the British Navy, who turned him over to Honduras. He was executed by firing squad.
Walker was only one filibuster, and his story is brilliantly told in The First Tycoon, The Epic Life of Cornelius Vanderbilk, by T.J. Stiles. His life is just one part of the catastrophe that United States citizens have inflicted on Central America, and illustrates the damage caused there by the twin destructive mindsets of manifest destiny and slavery.