Final answer:
The U.S. defeat of Spanish forces in the Philippines was achieved by Commodore George Dewey's fleet destroying a Spanish fleet at Manila Bay and coordination with Filipino insurgents, culminating in the signing of the Treaty of Paris.
Step-by-step explanation:
The United States defeated Spanish forces in the Philippines through a combination of superior naval power and coordination with Filipino insurgents. Commodore George Dewey's significant military maneuvers initiated the confrontation, when his fleet destroyed a Spanish fleet at Manila Bay without sustaining any American casualties. This early victory set the tone for the conflict.
Following the naval victory, Emilio Aguinaldo's Filipino insurgents isolated Spanish troops in Manila, making the arrival of U.S. troops a relief for the Spanish, who preferred to surrender to the Americans rather than the native fighters. The surrender led to the signing of the Treaty of Paris, with Spain granting independence to Cuba and ceding the Philippines, Guam, and Puerto Rico to the U.S. for $20 million. The war concluded with the supremacy of U.S. naval forces and set the stage for American expansion into the Pacific.