Introduction

The naval history of the Second World War in the Pacific is typically taught as Allied and Japanese military fleets engaged in air and surface combat across the theatre. But a critical component of the Allied strategy to defeat the Japanese empire was to sink, destroy, or otherwise neutralize the Japanese merchant fleet. Traditional histories of the Allied campaign to sink the Japanese merchant fleet have focused on the submarine effort, and not without good reason. Allied (particularly U.S.) subs sank over half of the merchant tonnage lost by the Japanese and did so utilizing a relatively small number of boats. Also, the U.S. submarine fleet endured disproportionately high per capita of losses in both men and lost vessels. Submarine service during the Second World War evokes a degree of romanticism. Submarine crews (all of whom volunteered for the “Silent Service”) endured a level of hardship and danger unqiue to their profession. Similarly, submarine skippers operated with a degree of freedom not enjoyed by other naval commanders. These factors have combined to inform a historiography which has largely ignored the multifaceted campaign effort. However, a computational look at the data shows a more complex relationship between Allied air, sub, and mining efforts. This article uses computational methods applied to the “Japanese Naval and Merchant Shipping Losses During World War II by All Causes,” a report prepared by a joint U.S. Army and Navy committee on all Japanese merchant vessels greater than 500 gross tons sunk by the Allies during the war. The report catalogues vessel type, tonnage, sinking date, location, sinking agent, and sinking country. As with all datasets, the report data is not without its issues. Despite its comprehensiveness, the data only catalogues sunk vessels, and no other types of Allied action and patrols. In this respect the data is only representative of operational outcomes, not necessarily the processes which brought about those outcomes. Despite its deficiencies, the dataset is an excellent medium with which to analyze the war in the Pacific.