Alfred Thayer Mahan was a United States naval officer and historian, born on September 27, 1840. He is best known for his influential work, *The Influence of Sea Power upon History, 1660-1783*, published in 1890. Mahan argued that naval power was crucial for national strength and global dominance, emphasizing the importance of a strong navy and overseas bases. Mahan's ideas significantly shaped naval strategy and policy in the late 19th and early 20th centuries, impacting countries like Great Britain and Germany. His theories contributed to the naval arms race prior to World War I and influenced military leaders and policymakers worldwide.