After more patrol duties and surviving the occasional air raid, Haguro escorted carriers at the Battle of the Philippine Sea, where she aided the sinking aircraft carrier Taihō, and fought in the Battle of Leyte Gulf, surviving the submarine and air attacks that sank several Japanese ships, and in turn damaging several US warships and helping to sink the destroyer USS Hoel while taking minor damage from shell and bomb hits.

Haguro was originally equipped with ten 20 cm (7.9-inch)/50 naval guns in five twin turrets, three forward and two aft, making her the most powerful heavy cruiser in the world at the time of her commissioning.

In October 1930, Haguro embarked on a voyage carrying Emperor Hirohito from Kobe to the battleship Kirishima from the 22nd to 25th,[2] Between 1931 and 1933 she was commanded by Nomura Naokuni who subsequently achieved flag rank.

[2] By the time of Japan's entry into World War II with the attack on Pearl Harbor on 7 December 1941, Haguro was en route to the Philippines as part of a large cover force to support Japanese landings.

At around 28,000 yards (26,000 m), Haguro fired her eight 203 mm (8 in) guns at the enemy ships, immediately targeting the Allied flagship, the Dutch light cruiser HNLMS De Ruyter.

The first hit the axillary motor room and started a small fire, killing one crewman and injuring six others, while the second over penetrated unarmored portions of the ship without exploding.

The hit immediately killed much of the cruiser's damage control team, started a large fire, and overwhelming flooding disabled her engines and De Ruyter stopped dead in the water.

[9][10] By this point, Haguro was almost entirely out of ammunition, left with enough rounds for 13 salvos and just 4 torpedoes, causing her to retire from the engagement while Myōkō and Ashigara and the destroyers Kawakaze and Yamakaze combined fire to sink Encounter.

[11] Pope temporarily escaped, but within two hours was crippled by aircraft from the light carrier Ryūjō[12] and then finished off by gunfire with the arrival of Ashigara and Myōkō.

This commenced on May 1 when Haguro alongside Myōkō and six destroyers departed Truk as part of a larger escort to the aircraft carriers Shōkaku and Zuikaku in what became known as the Battle of the Coral Sea.

Haguro arrived back at Truk on the 17th, and returned to Kure on the 22nd, then on the 27th arrived at Hashirajima in preparation for the Battle of Midway, where Haguro escorted a large troop convoy for the planned invasion of Midway Island, a convoy which was called off on June 6 after the battle turned into a devastating defeat which lost Japan four aircraft carriers and a heavy cruiser.

[2] Haguro did not sortie during July, only seeing her next action as an escort for Japanese aircraft carriers during the battle of the Eastern Solomons on August 24, coming under light air attacks but receiving no damage.

Haguro spent the rest of August and into September transiting between ports, surviving attacks by B-17 bombers without damage, before being docked for refit on October 5.

On November 27, Haguro departed Sasebo alongside Myōkō on a troop transport mission to Truk, then returned to Kure by the end of the year.

For the next few months, Haguro engaged in a series of peaceful patrol duties throughout the Indian Ocean, which failed to yield combat, finally returning to Yokosuka later that May, before escorting navy responses to the invasion of Attu until June when she was docked for refit which installed new sets of radar and several anti-aircraft guns.

At the end of September, Haguro attempted to track down the US navy task force 15, but failed to make contact, then took part in convoy escorting missions throughout October.

[2] After a very, very long series of patrol and escorting duties without seeing combat, Haguro finally saw some big action again on 1 November, as she was moored near Rabaul when the Japanese command hatched a plan.

Haguro and Myōkō, with an escort of the light cruisers Agano and Sendai and six destroyers, the Shiratsuyu, Shigure, Samidare, Hatsukaze, Naganami, and Wakatsuki, were tasked with intercepting and destroying the allied protection forces escorting American troop convoys destined to Bougainville Island in an attempt to replicate a battle of Savo Island style victory.

While underway, one of Haguro's floatplanes spotted her target, an American task force consisting of four light cruisers, USS Cleveland, Columbia, Denver, and Montpelier, escorted by 8 destroyers.

[3][17] However, the Japanese received far more damage than they inflicted, Sendai had already been blasted into a floating flaming wreck by gunfire from the four American cruisers and sank in a one sided massacre with most of her crew.

Spence then called upon Admiral Arleigh Burke's destroyer division 45, consisting of USS Charles Ausburne, Claxton, Dyson, and Stanly, to deliver the final blow to the crippled Hatsukaze, which they successfully finished off with gunfire.

Deciding to cut their losses, Haguro and the other Japanese ships retreated from the engagement, not only had they lost more tonnage than they damaged, but failed to disrupt the American landings in any way.

[2][18] Haguro returned to Okinawa on 22 June, and two days later was drydocked in Kure for refit, receiving 52 additional AA guns and upgraded type 13 and 22 radar.

[2][19] With three heavy cruisers and two destroyers out of the fight, the fleet regrouped into two circular formations, Haguro serving in the leading group centering around Yamato in anticipation of air attacks.

Meanwhile, the Myōkō was hit by an ariel torpedo which dropped her speed to 15 knots and forced her to retire, resulting in Vice Admiral Hashimoto transpiring his flag to Haguro as she continued on with the fleet.

[2][22][23][24][25] Haguro temporally retreated to conduct repairs, and after 8:30 returned to the battlefield, where she joined Tone in continuing to pound Kalinin Bay.

With the sinking of the heavy cruisers Chikuma, Chōkai, and Suzuya to air attacks, and the damaging of several more, while believing his ships had sunk at least two fleet carriers (if not more) and multiple cruisers and destroyers, Kurita ordered a withdraw, Haguro followed the other Japanese ships in retreating, during which Haguro spotted the formation of escort carriers that made up Taffy 2, but chose not to attack.

Despite helping to sink a destroyer and damaging several other ships, Haguro failed to engage her intended target of the American troop convoys, as with the rest of the fleet, rendering the battle of Leyte Gulf both a crushing tactical and strategic victory for allied forces.

On 4 March 2003, a group of specialized shipwreck divers operating off MV Empress discovered the wreck of Haguro in 67 metres (220 ft) of water in the Malacca Strait south of Penang.

2 turret is trained to starboard at approximately the 1 o'clock position, with its roof collapsed and both barrels and breeches missing, as they were not replaced after being damaged by a bomb at the earlier Battle of Leyte Gulf.