Knickerbocker Commodore chronicles the life of Rear Admiral John Drake Sloat, an important but understudied naval figure in US history. Born and raised by a slave-owning gentry family in New York's Hudson Valley, Sloat moved to New York City at age nineteen. Bruce A. Castleman explores Sloat's forty-five-year career in the Navy, from his initial appointment as midshipman in the conflicts with revolutionary France to his service as commodore during the country's war with Mexico. As the commodore in command of the naval forces in the Pacific, Sloat occupied Monterey and declared the annexation of California in July 1846, controversial actions criticized by some and defended by others. More than a biography of one man, this book illustrates the evolution of the peacetime Navy as an institution and its conversion from sail to steam. Using shipping news and Customs Service records from Sloat's merchant voyages, Castleman offers a rare and insightful perspective on American maritime history.