浅間丸
On a voyage departing from San Francisco on 6 January 1940 "Asama Maru" had 51 German citizens on her passenger manifest. On 21 January, she was intercepted in international waters from Nozaki Lighthouse, at the southern tip of the Bōsō Peninsula by the Royal Navy light cruiser . The British had received intelligence that crewmen from the scuttled German liner "Columbus" who had escaped to the United States had taken passage on "Asama Maru" in an attempt to return to Germany. In direct violation of Japan's neutrality and international law, the British Government had authorised the Commander-in-Chief, China Station to board, provided that the coast of Japan was not within sight. She initially refused to stop, but was forced to do so after "Liverpool" fired a blank round. An armed boarding party removed 21 of the ship's passengers, all former officers or technicians of Standard Oil tankers, claiming that they were German military personnel The Government of Japan formally protested the action, on the basis of Article 47, of the 1909 London Declaration, which states that only persons actually enlisted in the armed services of belligerent nations could be removed from the ships of neutral countries. Moreover, the fact that the incident had occurred so close to the shores of Japan further escalated tensions between the two countries. Despite the upsurge in anti-British sentiment in Japan, the government of Prime Minister Mitsumasa Yonai took a more conciliatory approach. In return for promising not to offer passage to certain categories of military age Germans in the future, the British agreed to return some of the detained passengers. On 29 February, as "Asama Maru" was departing Yokohama, nine of the previously captured German civilians were returned to "Asama Maru" by the British armed merchant cruiser .