Why did Spain lose the war in the 1500s?

In the 1500s, during the Age of Exploration, Spain became the most powerful country in Europe and likely the world. ... Spanish conquistadors such as Hernan Cortes and Francisco Pizarro conquered much of the Americas and claimed them for Spain.The Treaty of Paris ending the Spanish-American War was signed on December 10, 1898. In it, Spain renounced all claim to Cuba, ceded Guam and Puerto Rico to the United States and transferred sovereignty over the Philippines to the United States for $20 million.