Image Source: U.S. Navy
Nimitz entered the U.S. Naval Academy in 1901 and graduated in 1905, ranking seventh in a class of 114 midshipmen. Naval officers at the time were required to complete two years of sea duty before receiving their commissions, and Nimitz served aboard the battleship USS Ohio during this probationary period before being commissioned as an ensign.
His early assignments included duty in the Asiatic Fleet and eventually command of small gunboats and destroyers in the Philippines, where, still a young officer, he ran his vessel aground — an incident that resulted in a court-martial but did not derail his career. From there he moved into submarine service, a still-nascent branch of the Navy, commanding a succession of vessels and eventually an entire submarine flotilla. This period established his technical reputation, particularly in diesel engine design, and led to consulting work with civilian engine manufacturers that shaped Navy propulsion standards for years afterward.