The Noose Tightens Around Japan

Abstract

One of the main purposes of Japanese expansion was to procure raw materials. These materials needed to be transported to Japan by sea, and materials and men to defend the new acquisitions dispatched in the opposite direction. Japan had a sizeable merchant fleet, but had neglected the need to protect this traffic. The Navy was built for fleet actions, including the submarine force; there were few escort vessels, and methods of convoying and anti-submarine warfare were not developed until it was too late. From 1943 Vice-Admiral Lockwood’s Submarine Command in Pearl Harbor was able to deploy an increasing number of fine ocean-going submarines, which took a heavy toll of Japanese shipping. Supply to the island bases, then to Japan itself, was dislocated, with damaging impact on Japan’s domestic economy. The rubber, oil and other resources that were the reason for the war in the first place ceased to flow into Japan. Aided by radar and signals intelligence, the American submarine blockade on Japan by the end of 1944 was one of the most effective naval blockades ever mounted. Over 1,200 Japanese merchant ships were sunk, and 20 major warships, for a loss of 52 US submarines out of 288.