Description Fort Flagler, along with the heavy batteries of Fort Worden and Fort Casey, once guarded nautical entrance to Puget Sound. These posts, established in the late 1890's, became the first line of a fortification system designed to prevent a hostile fleet from reaching such targets as the Bremerton Naval Yard and the cities of Seattle, Tacoma and Everett. Construction began in 1897 and continued in one form or another until the fort was closed in 1953.