How many days did the Spanish-American War officially last?

The Spanish-American War officially lasted 109 days. The conventional count runs from the U.S. declaration of war on April 25, 1898, to the signing of the Protocol of Peace on August 12, which suspended hostilities.

The short conflict began after years of Cuban rebellion against Spanish rule and rising American concern over events in Cuba. The explosion of the USS Maine in Havana Harbor on February 15 intensified public pressure, although the cause of the disaster remained disputed. American victories at Manila Bay, San Juan Hill, and Santiago de Cuba quickly weakened Spain’s position.

The 109-day figure is a common historical shorthand, but dates can look slightly different depending on what is being measured. The U.S. blockade of Cuba began on April 21, and the peace protocol was scheduled to take effect on August 12; some accounts list the broader war as April 21–13, 1898, because of the timing of formal notifications. The final Treaty of Paris was signed on December 10, but that later treaty formally settled the war rather than extending the main fighting.