The Japanese raiders in the Indian Ocean were those vessels used by the Imperial Japanese Navy (IJN) during the Second World War to pursue its war on Allied commerce in that theatre. Possessing a powerful fleet of warships, prior to the start of World War II, the IJN had strategically planned to fight a war of fleet actions, and as a consequence delegated few resources to raiding merchant vessels. Nevertheless, in 1940, two passenger-cargo vessels – and – of the Osaka Shipping Line were requisitioned for conversion to armed merchant cruisers (AMC)s, in anticipation of the likely thrust southward by the Japanese. These vessels were subsequently used as merchant raiders attacking Allied commercial shipping along vital sea lanes of communication between Australia and the Middle East. Using their comprehensive armament and speed to their advantage, the raiders experienced a brief period of success. Japanese raiding in the Indian Ocean largely ceased by the end of 1942 after an action with a Dutch vessel, the and a Royal Indian Navy corvette, in which the Hōkoku Maru was sunk. Background Nations fighting Britain during both world wars in the 20th century devoted substantial effort to the disruption of oceanic trade as a means of weakening the British Empire. In late 1942, Axis activities in the Indian Ocean had virtually come to an end. German merchant raiders, originally disrupting the shipping lanes in these waters, had with few exceptions, been destroyed by the Royal Navy or begun the long journey home. By virtue of their powerful battle fleets, the Imperial Japanese Navy (IJN) had strategically planned to fight a war of fleet actions ("Guerre d'escadre"), and as a consequence delegated few resources to raiding merchant vessels ("Guerre de course"). Nonetheless, other than their successful sortie to Ceylon in April 1942, the Japanese Navy had decided to keep the pressure on the shipping lanes, primarily due to the Allies' ever-growing logistical strength in the war. Large and valuable tankers maintained a continuous stream of oil and other products from the Middle East to Australia and surrounding islands. The continuous pleas by the Germans possibly had a large influence on this decision, as the Indian Ocean was the primary area of operations in which the two Axis powers had the most physical coordination with each other, in regards to re-supply and the exchange of military (naval) intelligence. Japanese merchant raiders In 1940, two passenger-cargo vessels