Throughout the Gilded Age, America began to espouse a philosophy called the Monroe Doctrine, named for President James Monroe who first codified the idea. In short, the Monroe Doctrine was based on the premise of hemispheric hegemony, which is the idea that major nations have the right to oversee events in their sphere of influence, while outside nations must keep their distance. Throughout the 1890’s, Spain had violated this principal in their treatment of Cuba, which, at the time, was a territorial possession. At the request of Cuba, the United States began sending aid to them. When the American ship the USS Maine exploded while at anchor, the United States declared war on Spain. The major thrust of the war was in Cuba itself, where the United States sent the bulk of its troops. During the war, future President Theodore Roosevelt made a name for himself and his personal unit, the Rough Riders. Roosevelt’s popularity during the war went a long way in helping him secure the presidency in 1901. The Spanish, outmanned and outgunned, eventually agreed to a ceasefire, and during the treaty phase of negotiations, gave up both Cuba and the Philippines to the United States. The Spanish-American War was the first time that America had demonstrated its modern military prowess and established itself as a world power.