The USS Grenadier (SS-210) was not just another submarine. She was part of the United States Navy’s silent force—a fleet of underwater hunters that prowled the vast Pacific during World War II. Built at Portsmouth Navy Yard and launched in November 1940, Grenadier was a Tambor-class submarine, a major leap forward in undersea warfare. These boats were longer, sleeker, and more heavily armed than their predecessors. At over 300 feet in length, with ten torpedo tubes and improved surface speed, Tambor-class subs like Grenadier marked the transition from coastal patrol vessels to long-range oceanic predators. They could travel over 11,000 miles without refueling and could strike deep behind enemy lines, changing the tempo of war at sea.