During the Civil War, the United States Navy grew to be one of the largest naval forces in the world, and was at the forefront of developing new naval technology. However, in keeping with American tradition, the nation demobilized rapidly after the war, and soon fell far behind other powers (and non-powers) in terms of naval strength and effectiveness. In 1866, what would become over 15 years of stagnation was just beginning, and the Navy still retained some of its wartime resources. More relevant to some, it retained an enlarged officer corps which, when coupled with the concept of promotion by seniority rather than merit, would lead to a glacial climb "up the ladder" for veterans of the recent fighting.
This Navy was almost entirely an Eastern Seaboard/Atlantic Force, with the exception of a few far-flung squadrons.