Prior to the Japanese attack on Pearl Harbor, submarines in the Pacific Ocean were divided between the US Asiatic Fleet and the US Pacific Fleet. This distinction was eliminated when the United States entered World War II. While the rest of the US fleet recovered from the devastation of Pearl Harbor, the Submarine Force became indispensable. Using radical new technology, they managed to sink more than 55% of all Japanese shipping and naval forces, as well as successfully cutting off supply routes and neutralising the naval threat. This book explores how the Submarine Force severely impeded the seemingly unstoppable Japanese.