“1898; April 21. The Spanish Government considered the Joint Resolution of the United States of April 20 a declaration of war. U.S. minister in Madrid General Steward L. Woodford received his passport before presenting the ultimatum of the United States. A state of war existed between Spain and the United States and all diplomatic relations were suspended. President [William] McKinley ordered blockade of Cuba. Spanish forces in Santiago de Cuba mined Guantánamo Bay. The Spanish authorities in Cuba issued manifestos and other notices to the population and to the Spanish Army that a state of war existed with the United States.”
“Chronology of Cuba in the Spanish-American War,” Library of Congress, LOC.gov