Final answer:
Alfred Mahan defined the concept of sea power, emphasizing the importance of a strong modern fleet and global naval stations, which influenced the United States naval expansion and strategic policy in the late 19th and early 20th centuries.
Step-by-step explanation:
The individual who defined sea power emphasized the importance of understanding naval needs and championed a large, formidable Navy capable of mustering an overwhelming force to conquer the enemy's Navy is Alfred Mahan. As a naval theorist and historian, Mahan profoundly affected naval strategies with his seminal work, The Influence of Sea Power upon History, 1660-1783, published in 1890. In this work, he presented a compelling argument that the prowess and prosperity of great nations throughout history were invariably linked to their naval power.
Mahan underscored the necessity of a powerful modern fleet equipped with large ships and heavy guns, which would enable the United States not only to protect its commercial interests but also to emerge victorious in conflicts like the Spanish-American War. He advocated for the development of faster battleships and a global network of refueling stations, proposing strategic acquisitions, such as Hawaii, and the construction of a canal across Central America to facilitate fleet mobility.
Mahan's ideas reverberated through the corridors of power, influencing policymakers, including future President Theodore Roosevelt, and contributing to a significant naval expansion in the late 19th and early 20th centuries. Mahan's vision ultimately materialized as the United States embarked on broadening its reach, with accomplishments such as the strategic military bases in the Caribbean and the Pacific, and the transformation of the U.S. Navy into a world-ranked naval power.