The United States became an imperialist nation in the very late 1800's, the Americans wanted to expand over seas with their belief in manifest destiny. There were many factors that started American imperialism, they included; political and military competition including the creation of a strong naval force, economic competition among industrial nations and a belief in the racial and cultural superiority of people of Anglo-Saxon decent. The Spanish American War marked the appearance of the United States as a world power.
On the night of 15 February l898 the battleship USS Maine was shattered by an explosion, which sent the ship and two-thirds of her crew to the bottom of the ocean. This sparked a short war, known as the Spanish-American War, which was quickly decided by the two naval forces. On May first the U.S. Pacific Squadron under Commodore George Dewey arrived into Manila Bay, Philippine Islands, and destroyed the Spanish fleet. Months later, Admiral William Sampson repeated with a victory over the Spanish in a battle off Santiago, Cuba. America came out of the Spanish-American War as a major naval power. After having routed Spain the United States secured undisputed control of the American Mediterranean, the Gulf of Mexico, and the Caribbean. Puerto Rico was annexed. This sparked the great confidence in America.
The Boxer Rebellion signifies the effects of growing imperialism in the United States. Austria, France, Germany, Great Britain, Italy, Japan, and Russia all claimed exclusive trading rights to certain parts of China. They were dividing China into "spheres of influence." After achieving power of the Philippines the United States became an "Asian Power", and they hoped to take advantage of this trading empire emerging in China, however china was becoming fed up. While China was looking to close its borders to foreigners the United States was looking for ways to get in. Secretary of state, John Hay, had a plan of negotiation, since the American people would not accept force.