San Pedro Harbor, late September 1921. The Pacific Fleet’s new base was a place alive with the restless energy of a Navy in transition. Battleships and destroyers filled the anchorage, while a cluster of small, dark-hulled submarines rocked gently in their moorings beside the big tender USS Camden. The sun had set, but the harbor was far from quiet. Ashore, the city of Los Angeles was swelling into one of the nation’s fastest growing metropolises, and the Navy’s presence was both a symbol of American reach and a reminder of unfinished business after the First World War. For the sailors aboard USS R-6, the night of September 26 began as another routine round of preparations for training exercises. Within hours, however, it would end with their boat lying on the harbor bottom and two of their shipmates dead.