"Beginning in 2007, Kent decided to share his love of fortifications and soon began work on writing a field guide comprising the Harbor Defenses of San Francisco and its various elements built from 1890-1950. In 2011, Kent decided to completely update his original work with new and updated material, as well as correcting a number of errors and omissions found in the first edition. In 2015, Kent undertook an new endeavor in an effort to document the relatively small and lesser known coast defense milary reservations located with the Harbor Defenses of San Francisco. The fruit of this labor is his fourth book."--Rear jacket flap.