The Lopez Expedition of 1851 was an attempt led by Narciso López to invade and seize control of Cuba which was then part of the Spanish Empire. The force comprising 420 Cuban emigres and American volunteers landed in western Cuba, where the invaders were defeated and captured by the Spanish forces. López and many of the other prisoners were executed. It was part of a string of filibustering raids launched from American territory during the era, in violation of the Neutrality Act.

A filibuster, also known as a freebooter, is someone who engages in an unauthorized military expedition into a foreign country or territory to foster or support a political revolution or secession. The term is usually applied to United States citizens who incited insurrections across Latin America, particularly in the mid-19th century, usually with the goal of establishing an American-loyal regime that could later be annexed into, or serve the interests of, the United States. Probably the most notable example is the Filibuster War initiated by William Walker in Nicaragua in the 1850s.