|Ship Class||Taiyo-class Escort Carrier|
|Laid Down||14 Dec 1938|
|Launched||31 Oct 1939|
|Commissioned||31 May 1942|
|Sunk||17 Sep 1944|
|Displacement||17830 tons standard; 19500 tons full|
|Machinery||4 Kampon water-tube boilers, 2 Kampon geared steam turbines, 2 shafts, 1 rudder|
|Power Output||25200 SHP|
|Range||6,500nm at 18 knots|
|Armament||2x2x127mm L/40 Type 90 AA guns, 64x25mm L/60 Type 96 AA guns, 10x13.2mm L/76 Type 93 AA machine guns|
|Armor||25mm side belt over machinery spaces and magazines|
Contributor: C. Peter Chen
Originally built as the Nippon Yusen Kaisha passenger liner Yawata Maru, she was designed to rival European luxury liners that carried passengers from Europe to the Far East. She was never fully used as intended, however. When she was completed, Europe had just been engulfed in war, so Nippon Yusen had little choice but to put Yawata Maru on routes to Seattle and San Francisco, both in the United States. However, rising political tensions soon made these trans-Pacific routes unfeasible, either. Because her construction was partially subsidized by the Japanese government, when the Japanese Navy needed military transports, she was drafted for service in Oct 1941. Between 25 Nov 1941 and 31 May 1942, she was rebuilt at Kure, Japan as an escort aircraft carrier. She was placed under the command of Captain Keisho Minato. On 31 Jul 1942, she was officially named Unyo.
Unyo had no island, no catapult, nor arresting gear. She carried the initial armament of six 120-mm L/45 and four dual 25-mm L/60 Type 96 anti-aircraft guns.
As a carrier, Unyo was used mainly for training duties in Japan and aircraft ferrying duties to the outlying islands. In the latter role, she made port calls at Truk and Ulithi in the Caroline Islands, Saipan in the Mariana Islands, Palau Islands, Philippine Islands, Surabaya in Java, Balikpapan in Borneo, and Singapore throughout her WW2 career. Truk became a frequent destination; during her career, she made about 15 separate trips between Yokosuka, Japan and Truk. On 15 Dec 1943, she was assigned to serve as an escort carrier with an air group of 12 B5N Navy Type 97 carrier attack bombers.
On 19 Jan 1944, while sailing from Truk toward Yokosuka under the command of Captain Ikuya Seki, Unyo was hit by three torpedoes from American submarine Haddock. Her forward section was heavily damaged, but was able to sail to Saipan for temporary repairs. Under the escort of cruiser Takao, she sailed to Yokosuka, arriving on 7 Feb. After being re-assigned to Captain Shiro Hiratsuka on 1 Mar 1944, she went under repairs on 2 Apr 1944, which lasted until 28 Jun; during the repair, her anti-aircraft armament was updated to her final configuration.
On 1 Jul 1944, Captain Ikuzo Kimura took over as the commanding officer of the escort carrier. By this time, Truk had already been isolated, and the Mariana Islands were already under American attack, so she remained in Japan. On 14 Aug 1944, Unyo was assigned to the 1st Surface Escort Force. Between 13 Aug and 1 Sep, she completed her first escort mission with the 1st Surface Escort Fleet from Japan to the Philippine Islands with a stopover at Takao, Taiwan.
On 11 Sep 1944, Unyo and light cruiser Kashii escorted convoy HI-74 of five oil tankers and six escort vessels, which had come from Singapore and was destined for Japan. Amidst a heavy storm, just before midnight during the night of 16 Sep 1944, oil tanker Atsusa Maru was suddenly struck by the thus far undetected American submarine Barb and sank. At 0037 on 17 Sep 1944, Unyo was hit on the starboard side by two torpedoes from Barb. The first struck her stern at the steering compartment, and the second detonated in the engine room. She settled aft immediately, but damage control crews made promising progress in saving her. However, rough seas made her take in water at an accelerated pace. By 0730, she was listing heavily to starboard side, and the order to abandon ship was given by Kimura. She sank stern first at 0755, and Kimura went down with the ship. 55 officers and 706 men were saved. Accounts conflict as to how many lives were lost. Most accounts place the loss of lives at about 200, though some sources noted that losses were much lower.
Sources: Imperial Japanese Navy Page, Wikipedia.
Unyo Operational Timeline
|31 May 1942||Unyo was commissioned into service.|
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Winston Churchill, 1935