How was the naval battle of Guadalcanal affected by Japanese ships loading High Explosive shells rather than Armor Piercing?

Question

During the first Naval Battle of Guadalcanal an American flotilla of five cruisers and eight destroyers challenged a Japanese group of two battleships, one cruiser, and eleven destroyers that was planning to bomb America's "Henderson [Air] Field."

The Americans were outnumbered and outgunned, but the result of the battle was basically a draw. One disadvantage for the Japanese was that their ships' guns were loaded with high explosive shells (for bombardment), rather than armor piecing shells.

What difference did the Japanese using the "wrong" kind of shell make in the battle?

Answer 1

Based only on the terms in the question, I can conclude that High Explosive shells are less effective at piercing armor, such as that found on battleships. Wikipedia confirms this.

An armor-piercing (AP) shell is a type of ammunition designed to penetrate armor. From the 1860s to 1950s, a major application of armor-piercing projectiles was to defeat the thick armor carried on many warships.

. . .

With the introduction of the first ironclads in the 1850s and 1860s, it became clear that shells had to be designed to effectively pierce the ship armour. A series of British tests in 1863 demonstrated that the way forward lay with high velocity lighter shells. The first pointed armour-piercing shell was introduced by Major Palliser in 1863. Approved in 1867, Palliser shot and shell was an improvement over the ordinary elongated shot of the time. Palliser shot was made of cast iron, the head being chilled in casting to harden it, using composite molds with a metal, water cooled portion for the head.[23]

The remainder of that section is also instructive.

High Explosive (HE) shells are intended for antipersonnel use, and are defeated by armor. AP shells are required to damage a target protected by armor.

It appears that the Japanese did attempt to rearm.

Frantically the Type-3 incendiary shells were ordered switched to armor-piercing. A veritable "stampede" in the magazines resulted, for all knew that a hit on either battleship before the highly explosive bombardment shells were safely stowed could turn them into infernos. But by some providence the Japanese did not understand, Fortune gave them a reprieve of eight long minutes. (Note that this source asserts that they were armed with incendiary shells, not HE). Either HE or HEI would need to be restowed properly because detonation of one of these shells inside the ship would have been catastrophic.

The same source continues,

This gave Abe the vital time he needed to largely finish the switch of his main battery ammunition (though some incendiary shells were reported by the U.S. Navy), and assess the situation. Though confusion persisted about the precise location of the YUDACHI, the Japanese, unlike the Americans, could be sure the targets in front of them were enemy. Six minutes after sighting, Abe gave the order to illuminate with searchlights and to open fire. The action began at 0148 (Local time---Tokyo time was two hours earlier) when HIEI in concert with destroyer AKATSUKI and others snapped on searchlights to illuminate Callaghan's approaching force.

HIEI unleashed a truly devastating opening salvo, apparently hitting ATLANTA at the outset. Caught in the illumination, the ATLANTA and the SAN FRANCISCO behind were all but sitting ducks, spotlighted for all the Japanese fleet to see. But they were far from impotent, and were almost at once returning fire with equal gusto. Thus began what historian Paul Dull and others have referred to as "the most confused, close-ranged, and horrendous surface engagement of the war." It was also surreally brief. In reading of the detailed hard-fought action in multi-paged accounts, it is both startling and easy to overlook noting the fact that the time spanned from when HIEI and AKATSUKI snapped on their searchlights to the end of the action was barely a half hour.

At least this source seems to believe that the type of shell was not the critical factor.

Answer 2

HE had little to do with the outcome. Japan failed mainly because of American air power and Japan's refusal to press the attack.

Here is a diagram of a typical battleship, an Iowa class. As you can see, there's only armor over critical areas like the engine and armament. A shell hit anywhere else isn't going to need to penetrate much steel to deal damage. The cruiser San Francisco actually was disabled by HE, and barely escaped before AP shells could be loaded.

Wiki link

Hiei was unable to depress her main or secondary batteries low enough to hit Laffey, but Laffey was able to rake the Japanese battleship with 5 in (127.0 mm) shells and machine gun fire, causing heavy damage to the superstructure and bridge, wounding Admiral Abe and killing his chief of staff.[40]

As you can see, even small caliber shells and machine gun fire are effective against lightly armored areas.

Furthermore, the main weapon on the Japanese destroyers would be the Long Lance torpedoes. These were far better than anything the Allies had and were greatly feared.

The reason why Japan lost the first engagement had nothing to do with HE shells or the night action- which it won. Japan lost because it failed to press the attack. And furthermore, American air strikes after the battle ravaging the fleet. The subsequent engagements involving normal AP shells, which Japan won, were again strategically inconclusive because Japan withdrew afterwards.

There is one engagment were the shell type was important- at Jutland, British shells exploded early and were not as effective. But this was an even fight between well armored vessels.

Answer 3

I googled Japanese site from which I was expecting a good answer. This site might be so.

Okay, let's dig into his ( or her ) explanation.

In Japanese,

2342（午後11時42分）艦隊の前方 2,000ｍで警戒前進中の駆逐艦 　　「夕立」より敵艦見ゆの第一報、続いて旗艦「比叡」も前方 6,000ｍ 　　　に敵影発見、全軍に急報「方位 136度、敵らしき艦影見ゆ」を発し、 　　　同時に攻撃目標変更を下令。「全軍突撃、針路80度」。 　　　　2348、針路変更して暗夜の海面を敵艦目がけ各艦突撃開始、既に 　　　その距離２～４千メートル、米巡洋艦５隻アトランタ、サンフラン 　　　シスコ、ポートランド、ヘレナ、ジュノーと駆逐艦８隻が戦艦比叡、 　　　霧島、軽巡長良および駆逐艦11隻、入り乱れての乱戦である。 　　　　旗艦「比叡」は探照灯を照射し射撃目標を指示、自らも射撃開始、 　　　--- しかし、弾丸は３式弾である、通常弾と換装している暇など無かっ 　　　たのだ（註、３式弾は焼夷弾で破壊力小）--- 　　　　

Translated

2342, ( at PM 11:42 ) Yuudachi, one of the destroyers of the Japanese Imperial Army fleet which was patrolling 2,000 m in front of the fleet reported she had found enemy. In addition to it, the flagship, the battleship Hiei reported 6,000 m in front of her, she had found enemy. The fleet alerted every ship it had found supposed enemy at 136 degree. Then they set their path toward 80 degree to go attack. 2348, in the midst of the complete darkness all ships started firing upon American fleet. The distance between them was about 2,000 ～　4,000m, American fleet, composed of 5 cruisers, Atlanta, Sanfrancisco, Portland, Herena, Juno, and eight destroyers, Japanese fleet composed of 8 destroyers, 2 battleships, Hiei and Kirishima, light cruiser Nagara and 11 destroyers went into fierce battle. But the flagshipt Hiei, utilizing its search light started firing upon herself, --- but its bullets are San Shiki. The flagship had no time to change to normal bullets ( Noted ; San Shiki is an incendinary shell and its power to penetrate is light ).

Oh, fortunately or not I think I hit upon the very answer when translating, I think.

San Shiki, as you can see at the Wiki, mainly used for the anti aircraft, was used due to the flagship's timelessness of changing to "normal" bullet ( to normal aka Armor Piercing bullet ).

I wish I was able to contribute to any degree. ( It looks like this battle itself started with both ( American fleet and Japanese fleet ) had no enough time???

Thank you.

Answer 4

1st, the shells in a battleship are stacked in the hoists and in the handling rooms. So the 1st few salvos would have been incendiary. Any realistic amount of armor would have stopped those shells because they would have been set for point detonation. That doesn't mean that armor might not be displaced but the damage would have been limited if the armor belt were hit.

2nd, The fact that the Hiei's bridge was raked by 5" HE caused a lot of confusion and this affected the battle more than the type of shell being used.

3rd, Hiei was a battlecruiser and it showed. When San Francisco put at least one shell into her steering room. This is an area usually heavily armored on battleships for just this reason. Ultimately, leading to her sinking. At the ranges that the battle took place the range was so short and the Hiei's armor so thin that a major system was knocked out by a 250 lb AP cruiser shell.