ON JUNE 15, 1944 at 6:35 p.m., the American submarine USS Flying Fish operating in the Philippines Sea’s San Bernardino Strait spotted a large Japanese naval force heading east. One hour later – and farther south – the USS Seahorse raised its periscope and observed another large fleet of battleships and cruisers heading north into the Philippine Sea.
Both Flying Fish and Seahorse were part of an advanced screen of American submarines, tasked with keeping tabs on any and all Japanese naval movements.
The submarines had detected two converging elements of a massive Japanese naval force, intended to deliver the Kanti Kessen (decisive victory) the Japanese had sought, but failed, to inflict upon the U.S. Navy since the outbreak of the Pacific War, two-and-a-half years earlier.
The impetus for this Japanese naval offensive was the recent American assault on the Marianas Islands (namely the island of Saipan) which had begun on June 12 and would culminate three days later with a massive amphibious landing.
