Spanish–American War: The United States Navy begins a blockade of Cuban ports. When the U.S. Congress issued a declaration of war on April 25, it declared that a state of war had existed from this date.

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.

The Captaincy General of Cuba was an administrative district of the Spanish Empire created in 1607 as part of Habsburg Spain's attempt to better defend and administer its Caribbean possessions. The reform also established captaincies general in Puerto Rico, Guatemala and Yucatán.

The United States Congress is the legislative branch of the federal government of the United States. It is a bicameral legislature, including a lower body, the U.S. House of Representatives, and an upper body, the U.S. Senate. They both meet in the United States Capitol in Washington, D.C.

A declaration of war is a formal act by which one state announces existing or impending war activity against another. The declaration is a performative speech act by an authorized party of a national government, in order to create a state of war between two or more states.