Spanish–American War: The United States Congress declares that a state of war between the U.S. and Spain has existed since April 21, when an American naval blockade of the Spanish colony of Cuba began.

The Spanish–American War was fought between Spain and the United States in 1898. It began with the sinking of the USS Maine in Havana Harbor in Cuba, and resulted in the U.S. acquiring sovereignty over Puerto Rico, Guam, and the Philippines, and establishing a protectorate over Cuba. It represented U.S. intervention in the Cuban War of Independence and Philippine Revolution, with the latter later leading to the Philippine–American War. The Spanish–American War brought an end to almost four centuries of Spanish presence in the Americas, Asia, and the Pacific; the United States meanwhile not only became a major world power, but also gained several island possessions spanning the globe, which provoked rancorous debate over the wisdom of expansionism.

On 25 April 1898, the United States Congress declared war upon Spain. The ensuing Spanish–American War resulted in a decisive victory for the United States, and arguably served as a transitional period for both nations. Spain saw its days of empire fade, as the United States saw the prospect of overseas empire emerge. The war was ended by the Treaty of Paris signed on December 10 that same year.

A blockade is the act of actively preventing a country or region from receiving or sending out food, supplies, weapons, or communications, and sometimes people, by military force. A blockade differs from an embargo or sanction, which are legal barriers to trade rather than physical barriers. It is also distinct from a siege in that a blockade is usually directed at an entire country or region, rather than a fortress or city and the objective may not always be to conquer the area.

Cuba, officially the Republic of Cuba, is an island country in the Caribbean, comprising the island of Cuba, Isla de la Juventud, and 4,195 islands, islets and cays surrounding the main island. It is located where the northern Caribbean Sea, Gulf of Mexico, and Atlantic Ocean meet. Cuba is located east of the Yucatán Peninsula (Mexico), south of both Florida and the Bahamas, west of Hispaniola, and north of Jamaica and the Cayman Islands. Havana is the largest city and capital. Cuba is the third-most populous country in the Caribbean after Haiti and the Dominican Republic, with about 10 million inhabitants. It is the largest country in the Caribbean by area.