Japanese Merchant Shipping Routes 1941–45

As an island nation, Japan was heavily reliant on imports to supply its war effort. Its need for raw materials was a major contributing factor to Japan’s imperial expansion into Southeast Asia and the important oil producing areas of the Dutch East Indies. As Japan launched its offensives into Southeast Asia in 1941, it quickly overran the region, aided by its sizeable navy and merchant shipping fleet, which was one of the largest in the world at the time. The supply and defence of the many islands that had come under Japanese occupation depended on merchant shipping routes, which became a vital lifeline for the continued Japanese presence in the region. Merchant shipping losses mounted as the war went on and the US Navy focussed its forces in key areas, such as the waters around the north and east of the Philippines, which became known as ‘the Sea of the Devil’ to the Japanese.