In general, POW mail was an arrangement operated under the supervision of the camp commander (POW administrator), serving as a humanitarian system that allowed prisoners to send and receive letters. Today, it is widely used in various thematic philatelic exhibits. The basic principles of POW mail were established in the annex of the Convention with Respect to the Laws and Customs of War on Land, adopted at the First Hague Peace Conference held in The Hague, Netherlands, in 1899. It stated: *“Letters, money orders, valuables, and postal parcels sent to or by prisoners of war shall be exempt from all postal charges by the country of origin, destination, and transit.”*¹⁾ In this article, I would like to introduce POW mail exchanged by prisoners during the Russo-Japanese War, World War I, and World War II, in which Japan participated.
During the Russo-Japanese War²⁾, POW mail was used for the first time in the world under the above convention. [Figure 1] shows a POW letter sent to Russia by a captured Russian general imprisoned at the Hamadera (濱寺) POW camp, located in the southern part of Osaka during the war.³⁾ On the front, the bright red Western-language inscription “SERVICE DES PRISONNIERS DE GUERRE” is clearly printed, certifying that it is “free postal service for prisoners of war.” On the back, the POW letter bears a partially applied blue censorship handstamp of the Hamadera POW camp.⁴⁾ Accepted at Osaka Post Office, near the camp, on April 18, 1905, it was postmarked “Fengtian” (April 19) and sent on to Russia. It arrived in Russia on May 9. At that time, about 70,000 Russian POWs were scattered across 29 camps in Japan.⁵⁾ The Japanese army, in turn, had about 2,000 POWs held in Russia.
