Explores the life and times of John Drake Sloat, the US Navy Pacific Squadron commander who occupied Monterey and declared the annexation of California at the beginning of the war with Mexico. 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. “Knickerbocker Commodore is a first-rate scholarly biography of John Drake Sloat. In his study, Castleman presents a persuasive assessment of this important naval officer and his role in the controversial early days of the Mexican War in California.” — John H. Schroeder, author of Matthew Calbraith Perry: Antebellum Sailor and Diplomat “Written by a scholar and a former naval officer, Bruce Castleman has given us not only a well-balanced biography of John Drake Sloat but also a history of the US Navy from the time of the War of 1812 to the Civil War. In addition, his well-researched book provides an important contribution to the war with Mexico and the American conquest of Alta California through the actions and decision making of this ‘Knickerbocker Commodore.’” — Gary F. Kurutz, Curator Emeritus of Special Collections, California State Library “The Mexican-American War of 1846–47 was a war of foundational importance to the United States. Bruce Castleman’s biography of an important but little-known participant deftly captures the critical moment when America defeated its major continental rival. Even better, by thoughtfully tracing the entirety of Sloat’s life, the book winningly tells the story of the early American Navy from its tremulous beginnings in the Revolution to its steam-powered modernity in the Civil War. Castleman’s biography is of more than just a man; it is of an entire time in American history, and all the more useful for it.” — David J. Silbey, author of A War of Frontier and Empire: The Philippine-American War, 1899–1902