Short Abstract

The research analyzes Japan’s civilian exchange with the U.S. during WWII, arguing that it began as an irregular exchange of businessmen rooted in prewar policy, but shifted after 1942 toward convention-based treatment of internees, leading to the abandonment of further exchanges.

Long Abstract

This research examines how the Japanese government conceptualized and implemented civilian exchange and repatriation during the Pacific War, focusing on the U.S.–Japan exchange ship between 1941 and 1944. Although Japan justified the exchange as “conforming” to the 1929 Geneva Convention, that convention neither defined civilians nor provided for their exchange. This legal ambiguity, combined with the absence of a clear bilateral agreement on eligible categories, rendered civilian exchange an inherently irregular form of wartime diplomacy.

Drawing primarily on records of the Japanese Ministry of Foreign Affairs, this study situates the exchange ship within Japan’s broader prewar and wartime repatriation policies rather than treating it as an isolated humanitarian initiative. It argues that Japan’s initial motivation for including civilians stemmed from prewar efforts to repatriate businessmen and financial personnel, whose return was considered economically and strategically valuable. Examination of exchange lists and negotiation processes reveals that the Ministry, together with former embassies and protecting powers, exercised strict control over selection, prioritizing state utility over humanitarian considerations.

The research further traces a critical policy shift after 1942. Following the second exchange in 1942, the establishment of the Bureau in Charge of Japanese Nationals in Enemy Countries marked a reclassification of Japanese civilians in the United States as “prisoners” under the Geneva Convention framework. This conceptual transition—from selective, temporary exchange toward convention-based negotiations over internee treatment—coincided with the effective abandonment of further exchange ships.

By highlighting the tension between irregular diplomatic negotiations and international legal frameworks, this research argues that both the operation of the exchange ships and their eventual termination cannot be explained solely in military or political terms. Rather, they reveal deeper inconsistencies in Japan’s repatriation policy and the unresolved legal status of civilians in wartime—an issue that continues to resonate within international humanitarian law.