Admiral George Dewey, based in Hong Kong, was given the order to engage the Spanish fleet at Manila in the Philippines.
The official cause of the war was the destruction of the USS Maine outside Cuba. The U.S. blamed the sinking of the ship on a Spanish mine.
In response, the U.S. declared war against Spain on April 25, 1898.
Here, shellbacks sailors who had passed the equator relax after a day's worth of heavy training.
Dewey drilled his fleet ceaselessly in order to have them prepared to fully dismantle the Spanish force.
The entire battle lasted only a little over six hours...
... During which time Dewey's fleet stopped to take a three hour lunch break.
The outcome of the Battle of Manila was Spain's complete forfeiture of the Philippines.
The U.S. did not lose a single sailor at the Battle of Manila. Here, U.S. Marines stand at attention.
After the battle, U.S. sailors raised the American flag over Manila.
Although the Battle of Manila only took six hours, it took additional months to clear the Philippines of insurgents.
Aside from the Philippines, the U.S. also sent ships to blockade Cuba and Guam.
Guam, unaware that the U.S. and Spain were at war, surrendered immediately.
Spain hung onto Cuba for as long as it could, but eventually surrendered. The Spanish-American War lasted only four months and decisively proved the U.S. could function as a world power.
Dewey's victory was the first U.S. military victory against a foreign enemy since the War of 1812.
The Reina Cristina was the flagship of the Spanish Navy in the Pacific. Here, it's crew members pray before battle.