Immediately after the end of the Spanish-American War in 1899, a three-year guerrilla war between the United States and its new territory of the Philippines began. What caused this war? The United States had, after all, legitimately bought this archipelago from Spain for $20 million.
During the Spanish-American War, the United States had told the Filipinos it was fighting to free them from Spain. But after the Spanish surrender, American newspapers and politicians began a campaign to "Keep the Philippines."
Businessmen saw Manila as a center for trading with the great market of China. Military officers wanted an outpost in Asia.
President McKinley was undecided for a time. The, he told a group of his fellow Methodists, he prayed for guidance and decided to “take them all, and to educate the Filipinos, and uplift and educate and Christianize them.”
Filipinos had been Catholics for several hundred years, and they saw no need to be "Christianized" by the United States. Emilio Aguinaldo, who had led the revolt against Spain, now found he had to defend his country against its “liberators.” A fierce guerrilla war followed.
The United States won the war and set up an American-controlled government in 1901. But Americans from every political party, region, and profession were outraged by the action.