Japanese cruiser Mikuma

Mikuma in Kagoshima Harbor, 1939

Mikuma was completed at Mitsubishi's Nagasaki shipyards[4] on 29 August 1935.[3]

Beginning in 1939, Mikuma was brought in for substantial reconstruction, replacing the triple 155-millimetre (6 in) turrets with twin 203 mm (8 in) guns (the 155 mm turrets going to the battleship Yamato). Torpedo bulges were also added to improve stability, but the increased displacement caused a reduction in speed.[1]

Mikuma participated in the occupation of Cochinchina, French Indochina, after Japan and Vichy French authorities reached an understanding on use of its air facilities and harbors from July 1941, from its forward operating base on Hainan. At the time of the attack on Pearl Harbor, Mikuma was assigned to cover the invasion of Malaya as part of Cruiser Division 7 under Vice Admiral Jisaburo Ozawa's First Southern Expeditionary Fleet, providing close support for landings of Japanese troops at Singora, Pattani and Kota Bharu.[3]

In December 1941, Mikuma was tasked with the invasion of British Borneo, together with Mogami, covering landings of Japanese troops at Miri and Kuching.[5] In February 1942, Mikuma was tasked with covering landings of Japanese troops in Sumatra and Java.[6] On 10 February, Mikuma and Chōkai were attacked by the submarine USS Searaven, which fired four torpedoes, but missed.

At 2300 on 28 February 1942, Mikuma and Mogami, destroyer Shikinami, light cruiser Natori and destroyers Shirakumo, Murakumo, Shirayuki, Hatsuyuki and Asakaze arrived and engaged the cruisers USS Houston and HMAS Perth with gunfire and torpedoes after the Allied vessels attacked Japanese transports in the Sunda Strait. At 2355, Houston scored hits on Mikuma that knocked out her electrical power, but it was quickly restored. During the battle, Mikuma lost six men and eleven others were wounded. Both Houston and Perth were sunk during the engagement, as was transport Ryujo Maru with IJA 16th Army commander Lieutenant General Hitoshi Imamura—although the general survived the sinking.[3]

In March, Mikuma and Cruiser Division 7 were based at Singapore to cover Japanese landings in Sumatra[6] and the seizure of the Andaman Islands.[7]

From 1 April 1942 Cruiser Division 7 based from Mergui joined with Cruiser Division 4 to participate in the Indian Ocean raids. Mikuma, Mogami and destroyer Amagiri detached and formed the Southern Group, which hunted for merchant shipping in the Bay of Bengal, while Chōkai, Destroyer Squadron 4's light cruiser Yura and destroyers Ayanami, Yūgiri, Asagiri and Shiokaze covered the northern areas. During the operation, the Southern Group claimed kills on 7,726-ton British passenger ship Dardanus and 5,281-ton British steamship Ganara and the 6,622-ton British merchant vessel Indora,[8] en route from Calcutta to Mauritius.

On 22 April, Cruiser Division 7 returned to Kure, and Mikuma went into dry dock for overhaul. On 26 May, Cruiser Division 7 arrived at Guam to provide close support for Rear Admiral Raizo Tanaka's Midway Invasion Transport Group. Mikuma's crew was advised that upon the completion of the Midway operation they would proceed to the Aleutian Islands and from there to Australia.

On 5 June, Admiral Isoroku Yamamoto, CINC of the Combined Fleet ordered Cruiser Division 7 to shell Midway in preparation for a Japanese landing. The Mikuma at the time was captained by Captain Sakiyama Shakao, former skipper of the cruiser Abukuma. Cruiser Division 7 and DesDiv 8 were 410 miles (660 km) away from the island, so they made a high-speed dash at 35 knots (65 km/h). The sea was choppy and the destroyers lagged behind. At 2120, the order was canceled; however, due to a mixup, Cruiser Division 7 did not receive the order till 0210 the following day, when it was just 50 miles (80 km) off Midway. This placed Cruiser Division 7 within range of the submarine USS Tambor, which was spotted by the cruiser Kumano. Kumano signalled a submarine alert to the formation and directing the ships to conduct evasive maneuvers to the left. The squadron was thrown into confusion. Kumano turned sharply to port for a short time, heading west, before turning slightly starboard back to north. Suzuya followed her but coursed slightly less to port. She found herself steaming directly for Kumano but turned sharply to starboard and narrowly avoided colliding with the Kumano. Mikuma attempted to mirror the movements of Suzuya, turning to port and then turning to port further more after witnessing Suzuya maneuvering to avoid the formation's flagship (to avoid being entangled with the flagship). Mogami at the rear of the formation had made a turn to port and maintained a stright course heading north-west. Mikuma's final turn to port had brought her directly into the course of the Mogami. In the darkness, Mogami did not sight the Mikuma until she was very close to the Mogami, moving ahead across her starboard bow. Captain Soji of the Mogami attempted a last-second sharp turn to port but it was too late. This resulted in a collision in which Mogami rammed Mikuma's portside, below the bridge. Mogami's bow caved in and she was badly damaged. Mikuma's portside oil tanks ruptured and she began to spill oil, but otherwise her damage was slight, partially thanks to the last-second portside turn that deflected the Mogami's bow along an angle from the Mikuma's portside. With her damaged bow, Mogami could make only 12 knots at the time being, and was largely unwiedly and clumsy. The destroyers Arashio and Asashio of DesDiv 8, which had steamed ahead with the Suzuya and Kumano at high speed to flee the range of Midway's aircraft, were radioed by Kurita to reverse course and escort Mogami and Mikuma. At 0630, a PBY Catalina spotted the stragglers, thanks to the massive oil trail leaking from Mikuma, and radioed their coordinates to Spruance. Throughout the day, in an aura of great confusion, many American sighting reports would misidentify one of the two ships as a battleship. While other sightings of the flagship of CruDiv 7 steaming at high speed to the north-west, combined with the reports of battleships and suspicions of a 5th Carrier lurking about, led to great consternation to Spruance and his staff at Task force 16, who himself thought that the faster force steaming northwest was the one that contained the battleship. Midway wasted no time after receiving the report and launched the remnants of VMSB-241 containing 12 dive bombers (6 SBD Dauntlesses and 6 SB2U's divided in two wings). The aircraft travelled the short distance of 40 miles to their target and found the two cruisers. Despite her damaged bow and greatly reduced speed, the Mogami began evasive maneuvers along with the Mikuma and received no hits from the dauntless section. Capt. Richard Fleming, in command of the vindicator section, led his bombers in a glide bombing attack instead. The two cruisers were responding with accurate and effective anti-aircraft fire, and managed to shoot down Fleming's bomber. Almost as soon as this attack ended, a pack of eight B-17 level bombers operating out of Midway, led by Lt. Col. Brooke E. Allen, arrived to attack the two cruisers. They attacked in two sections of 4 aircraft and dropped a total of 39 bombs around the two ships with no hits. This attack concluded at around 0830.

Mikuma shortly before sinking

Mikuma burning after being bombed by American carrier planes, just before sinking. Note her completely destroyed midsection.

Japanese cruiser Mikuma seen burning from a Dive Bomber. Mogami is visible to the right, and a destroyer faintly visible between them

The following morning, 6 June 1942, Mikuma and Mogami were still heading directly due east instead of North-West where the combined fleet was converging, hoping to reach within the 700km range of Wake island's fighter air cover. Hornet's 26 dive bombers arrived first, having being already spotted in their carrier's flight deck in advance, and at first ignored the two cruisers and searched for the alleged battleship ahead of this force, but having found nothing and circled back to the two cruisers and commenced their attacks. Mikuma and Mogami were attacked by the dive bombers. All bombs on Mikuma missed, but two bombs hit the Mogami, crashing on top of one of her No.5 8-inch turrets and the aircraft deck, respectively. The latter bomb could have caused fatal damage to the Mogami as it started a fire in the torpedo room below the aviation facility, but Mogami's damage control officer had previously ordered all torpedos jettisoned. Accurate anti-aircraft fire from the force shot down two of Hornet's SBD Dauntlesses. Spurred down by the urgency of the action, the captain of the Mogamii pushed the damaged ship's speed up to 20 knots to hurry out of the danger zone. At 1045 a composite force of 31 dive bombers launched from the Enterprise to seek the purported battleship in the area spotted the two stragglers. The force was escorted by 12 Wildcats and 3 TBM Devastator torpedo bombers. The force was under the command of Wallace "Wally" Short of the Yorktown (some of her aircraft had been forced to land at Taskforce 16 after their ship was abandoned). The dive bombers, once again, bypassed CruDiv 7 to search for the battleship, which was not located. The Wildcats escorting the formations approached the cruisers and received accurate anti-aircraft fire that forced them to retreat to a safe distance. The Wildcat formation leader radioed to the dive bombers that one of the ships appeared to be a battleship (perhaps owing to the hazy contrast between the two cruisers presented by Mogami's shattered bow) and the dive bomber formation reversed course to attack the formation. Willy Short, leading the dive bombers, wanted to circle behind the formation and attack with the sun behind them, as was a favored dive bombing practice. But his rear section of the formation, VB-3, detached itself and attacked the rearmost cruiser in the formation (The Mogami), planting 2 bombs in her at 1230. The rest of the dive bombers under Short attacked the Mikuma from an altitude of 14,000 feet, and caught her as she was coming out of her sharp starboard turn. Cascading through a fiery torrent of her anti-aircraft fire, the bombers delivered a hit that crashed on top of her No.3 turret. The explosion killed many of the officers on the bridge, including the commander of the starboard anti-aircraft batteries, and injured her captain severely enough to render him unconscious. The Mikuma's executive officer Takashima Hideo took command of the cruiser in the meantime. An additional bomb hit crashed through the deck and disabled the starboard forward engine rooms. Immediately after, two bombs hit her aviation deck and exploded in the port aft engine room, starting a fire near her torpedo room. The Mikuma was now dead in the water. The attacking planes left (The three TBM devastator torpedo bombers did not join the attack, having being instructed to not attack anything that can respond with anti-aircraft fire). At 1358, the fire amidships the Mikuma reached the Type 93 Torpedoes stored there and triggered a chain of massive secondary explosions, putting to rest the hitherto hopes among the formation of towing the ship out of danger. At 1420 the Mogami radioed to the combined fleet that the Mikuma was in a sinking condition. The secondary explosions left the Mikuma's aft-amidships section and the aviation facility unrecognizable. The mast and superstructure atop the bridge collapsed and crashed into the conflagration in the aviation compartment. Though it wasn't obvious at the time, the bomb hit on the port machinery spaces had also ruptured the ship below the waterline, and she began taking on water. The Mikuma continued trying to bring her fires under control, but approximately 30 minutes later the ship's executive officer Takashima came to the conclusion that there was no hope of saving the ship now that she was slowly settling in the water and gave the order to abandon ship. Takashima ordered the repair parties to throw shoring wood and other materials overboard to construct life rafts. Mogami and Arashio were close to the Mikuma but maintained a safe distance as the Mikuma was still burning and exploding, so the crews of the Mikuma would have to swim over to the ships or use life rafts and launchers to reach the Arashio and Mogami. In the meanwhile Asashio patrolled in a circle around them to screen the ships from air or submarine attack. The ship's severely wounded captain Sakiyama was lowered on the first life raft, closely followed by the ship's paymaster and air officers, who took with them the ship's important documents. The rafts were launched towards the direction of the Arashio. Takashima remained in the ship's smoke-filled bridge, choosing to go down with the ship. The ship's main battery fire control director commander, Lt. Koyama Masao, also refused to leave the ship, choosing to instead commit Hara-Kiri on top of the forward gun turret, ashamed that his guns did not have a chance to smash the enemy.

A few minutes after Takashima gave the order to abandon ship, the ships were set upon by yet another dive bombing attack. At 1445, 23 Dauntlesses from the Hornet that were launched at 1330 arrived over the hapless formation. The Arashio and Mogami immediately commenced evasive maneuvers, leaving behind them many of the Mikuma's crews in the water who were still making their way to their accompanying ships. The dive bombers commenced their attack at 1500. The Mogami and Arashio did not have enough time to get underway and were both hit. The burning Mikuma was also hit. Arashio was hit by a bomb, which tragically exploded among the surviving crew of Mikuma that she had just picked up out of the water, killing 37 men outright and damaging her steering ability badly enough to force the destroyer to switch to manual steering and wounding Cdr. Ogawa Nobuki, commander of DesDiv8.[9] While the Mogami received a hit near the seaplane deck, which started a fire near the sick bay and killed almost all of the ship's doctors and their orderlies outright. The fire was quickly contained at the cost of the life of most of the injured and wounded men in the sick bay. Asashio was not hit by the bombing attack but lost 22 men to strafing. Realizing the urgency of the situation, captain Akira Soji, then commanding the detachment, communicated to the combined fleet to inform them of the attack, and immediately set course west to vacate the area before more air attacks occurred, leaving most of the Mikuma's crew in the water, the Mogami and the two destroyers of DesDiv8 sailed away from her, having had time to rescue only 239 of her crew, including her dying captain Sakiyama. The Mikuma continued to drift and burn for at least 4 more hours in her morose state. Owing to the great confusion among American sighting report the past 2 days, Admrial Spruance of Task Force 16 ordered two recon Dauntlesses with cameras launched from Enterprise at 1553 to ascertain whether this damaged ship was indeed the alleged battleship reported by multiple reconnaissance airplanes. The Dauntlesses arrived over the burning Mikuma at 1715, just before dusk, and took several photographs of her at extremely low altitude, and recorded footage of her as well. The Dauntlesses recorded her position at 29°-28'N, 173°-11'E before leaving her. A survivor recalled that the Mikuma's port list began increasing rapidly at dusk, and at approximately 1930, she finally turned over on her portside and sank at 29°20′N 173°30′E. She was the first Japanese cruiser to be sunk during the war. The Mikuma Only 188 of the Mikuma's crew survived the ordeal; her captain also succumbed 3 days later to his wounds while he was aboard the Suzuya. Captain Soji later ordered the Asashio to reverse course and go back to the Mikuma and make every effort to save any of her surviving crews. The Asashio made her way back to the Mikuma's location but found nothing, and promptly returned to CruDiv7, according to her log she found nothing but a great puddle of oil and "not one survivor could be rescued".[10] Although 2 days later, on June 9th, two of Mikuma's crews would be rescued by the USS Trout, the two were chief radioman Yoshida Katsuichi and third class fireman Ishikawa Kenichi. The two were onboard a life raft and originally numbered 17, but gradually as they succumbed to their wounds or malnourishment, only Ishikawa and Yoshida survived. Yoshida was suffering from broken ribs, while Ishikawa was in "good health".[11]

Owing to the secrecy and attempted cover-up of the disaster at Midway, the General Navy Headquarters would list the Mikuma as "heavily damaged" rather than sunk, and temporarily listed as "unmanned" before being struck off the navy list at August 10 1942.

• Campbell, John (1985). Naval Weapons of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-459-4.
• L, Klemen (2000). "Forgotten Campaign: The Dutch East Indies Campaign 1941–1942".
• Lacroix, Eric & Wells II, Linton (1997). Japanese Cruisers of the Pacific War. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-311-3.
• Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). Annapolis, Maryland: Naval Institute Press. ISBN 1-59114-119-2.
• Watts, Anthony J. (1967). Japanese Warships of World War II. Doubleday & Company.
• Whitley, M. J. (1995). Cruisers of World War Two: An International Encyclopedia. London: Cassell. ISBN 1-86019-874-0.