This document provides an overview of America's emergence as an imperial power in the late 19th century. It discusses the shift from isolationism to imperialism and interventionism under the new diplomacy. It then focuses on the Spanish-American War of 1898, covering the tensions between the US and Spain over Cuba, the sinking of the USS Maine, the role of yellow journalism in stirring up pro-war sentiment, and the key battles that resulted in US victory and the acquisition of territories like the Philippines, Puerto Rico and Guam.