''Aso Maru'' (''Japanese:'' 阿蘇丸) was a Japanese cargo ship that was requisitioned by the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

and converted into an auxiliary

gunboat A gunboat is a naval watercraft designed for the express purpose of carrying one or more guns to bombard coastal targets, as opposed to those military craft designed for naval warfare, or for ferrying troops or supplies. History Pre-steam ...

History

She was laid down 20 November 1931 at the

Kobe Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, whic ...

shipyard of Mitsubishi Zosen K.K. for the benefit of

Mitsui O.S.K. Lines Mitsui O.S.K. Lines ( ja, 株式会社商船三井, Kabushiki-gaisha Shōsen Mitsui; abbreviated MOL) is a Japanese transport company headquartered in Toranomon, Minato, Tokyo, Japan. It is one of the largest shipping companies in the world. ...

(MOL). She was launched on 26 March 1932, completed on 15 April 1932, and registered in

Osaka is a designated city in the Kansai region of Honshu in Japan. It is the capital of and most populous city in Osaka Prefecture, and the third most populous city in Japan, following Special wards of Tokyo and Yokohama. With a population of 2. ...

. She worked as a cargo ship until 16 December 1940, when she was requisitioned by the

for service as an auxiliary gunboat. On 15 January 1941, her outfitting was completed at the

Sakurajima Sakurajima ( ja, 桜島, literally "Cherry Blossom Island") is an active stratovolcano, formerly an island and now a peninsula, in Kagoshima Prefecture in Kyushu, Japan. The lava flows of the 1914 eruption connected it with the Ōsumi Peninsula ...

facility of Osaka Iron Works and she was assigned to the

Maizuru Naval District was one of four main administrative districts of the pre-war Imperial Japanese Navy. Its territory included the entire Sea of Japan coastline from northern Kyūshū to western Hokkaidō. History The strategic importance of the location of Maizur ...

. Her two sister ships, ''Fuji Maru'' and ''Kiso Maru'', were also requisitioned, the former as a subchaser and the latter, as a gunboat. On 10 April 1941, she was assigned to the 2nd Base Force,

Third Fleet The United States Third Fleet is one of the numbered fleets in the United States Navy. Third Fleet's area of responsibility includes approximately fifty million square miles of the eastern and northern Pacific Ocean areas including the Bering ...

, as part of the 3rd Gunboat Division (along with gunboats '' Kiso Maru'' and '' Nampo Maru'') based at Takao,

Formosa Taiwan, officially the Republic of China (ROC), is an island country located in East Asia. The main island of Taiwan, formerly known in the Western political circles, press and literature as Formosa, makes up 99% of the land area of the territorie ...

Invasion of Batan Island

The 3rd Gunboat Division was assigned to the Batan Island occupation force which began simultaneously with the

Japanese attack on Pearl Harbor The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, ju ...

tasked with establishing an air base to support future operations against American forces on

Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...

during the invasion of the Philippines. On 8 December 1941, the occupation force met off the coast of Batan Island consisting of the 3rd Gunboat Division along with the 52nd Subchaser Division ( ''Shonan Maru No. 17'', ''Takunan Maru No. 5'', '' Fukuei Maru No. 15''), the 53rd Subchaser division (, ''Kyo Maru No. 2'', ''Kyo Maru No.11''), the 54th Subchaser Division ('' Nagara Maru'', ''Shonan Maru No. 1'', ''Shonan Maru No. 2''),

Imperial Japanese Army The was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor o ...

transport ''Teiun Maru'' (carrying part of the 24th Airfield Battalion),

transport ''Kumagawa Maru'' (carrying 490 men of the Sasebo

Special Naval Landing Forces The Special Naval Landing Forces (SNLF; ja, 海軍特別陸戦隊, Kaigun Tokubetsu Rikusentai) were naval infantry units of the Imperial Japanese Navy (IJN) and were a part of the IJN Land Forces. They saw extensive service in the Second Sino ...

), destroyer , four s (''Chidori'', ''Manazuru'', , ''Hatsukari''), two s (''W-13'', ''W-14''), two patrol boats ( ''Patrol Boat No. 1'', ''Patrol Boat No. 2''), two s (''Kamome'', ''Tsubame''), and seaplane tender, '' Sanuki Maru'' escorted by destroyer .Niehorster does not list ''Teiun Maru'' as taking part in the operation. Combinedfleet.com does not note the participation of the three gunboats although Niehorster does and Japanese primary sources via Hyperwar indicate three gunboats took part

Sinking

On 9 May 1943, she was sunk by the US submarine at () off the southwest coast of

Negros Island Negros is the fourth largest and third most populous island in the Philippines, with a total land area of . Negros is one of the many islands of the Visayas, in the central part of the country. The predominant inhabitants of the island region a ...

References

{{DEFAULTSORT:Aso Maru 1932 ships Ships built by Mitsubishi Heavy Industries Maritime incidents in May 1943 Auxiliary ships of the Imperial Japanese Navy