Significance of the Battle of Midway

[VBF-13]

Take a look at this satellite image of Midway Atoll. Where are the port facilities, particularly deep anchorages and fuel storage, sufficient to handle aircraft carriers from an operational perspective?

The occupation force was just that...to occupy the atoll. If you don't occupy something, someone else will take it while you're back is turned. The only potential use for Midway is as a base for seaplane operations. There's no way you could launch an offensive operation from Midway.

OK, but I was thinking more in terms of the reasonably-foreseeable future, say, a strike within a matter of months. The ships didn't need to dock at any ports for that, they needed to lick their wounds, and be supplied, while they were at it. They'd have fresh water, and, in the longer term, crops. I'm using my imagination, now, not drawing on any authority for that proposition. Your proposition makes sense to me, don't get me wrong. It's just a little hard for me to shake off my proposition without any record extant on those intentions.

 

[RCAFson]

Take a look at this satellite image of Midway Atoll. Where are the port facilities, particularly deep anchorages and fuel storage, sufficient to handle aircraft carriers from an operational perspective?

The occupation force was just that...to occupy the atoll. If you don't occupy something, someone else will take it while you're back is turned. The only potential use for Midway is as a base for seaplane operations. There's no way you could launch an offensive operation from Midway.

The USN's primary use for Midway was as a submarine refuelling and forward submarine support base. It is about 2200nm to Japan from Midway versus ~3300nm from Pearl Harbor, and it was USN subs, after they sorted out their torpedo problems, that began to strangle IJ marine trade. If Japan had Midway they could use it to interdict USN subs and at the same time refuel their own.

 

[VBF-13]

The USN's primary use for Midway was as a submarine refuelling and forward submarine support base. It is about 2200nm to Japan from Midway versus ~3300nm from Pearl Harbor, and it was USN subs, after they sorted out their torpedo problems, that began to strangle IJ marine trade. If Japan had Midway they could use it to interdict USN subs and at the same time refuel their own.

That may very well be. Look at how they pounded Wake and just kept coming at it, relentlessly. They weren't trapping any carriers, there. What was Midway to them but the same thing as Wake?

 

[drgondog]

Hello,
At one of the current threads, the opinion was stated that US victory in the Battle of Midway was a tactical one. Didn't want to derail that thread, so maybe we could discuss the importance of that battle here.
I'll kindly ask that flag waving should be kept on minimum; thanks I'll also ask the moderators to keep this thread in this subforum, if that's o.k.

IMHO Midway and Stalingrad were the two Definitive turning points of the war. Up to either confrontation, the Axis held the initiative. Afterwards marked a slow but inexorable retreat from high water marks for both the Japanese and Germany.

 

[buffnut453]

That may very well be. Look at how they pounded Wake and just kept coming at it, relentlessly. They weren't trapping any carriers, there. What was Midway to them but the same thing as Wake?

Because the Wake operation wasn't aimed at trapping the American carriers. Operation MI had precisely that objective.

Using Midway as a submarine base makes much sense, indeed it's probably the only useful function for it, but such a function won't lead to an attack against Hawaii. You talk of resupplying carriers at Midway - where are the supplies going to come from, even for submarines? The stores have to be transported there which is exactly the point I'm making - the Japanese had tremendous difficulties keeping their isolated outposts resupplied. What was (and often still is) depicted as a red overlay covering most of the Pacific was, in reality, a series of isolated, unsupported locations that could be bypassed unless needed for strategic basing....which was exactly what the Pacific Fleet did for real.

 

[The Basket]

Midway was about getting the Pacific fleet to battle.
Odd the Japanese went 4 carriers.
At Pearl and Ceylon they went 6.
Perhaps indicative of a larger picture.

 

[Garyt]

Midway was about getting the Pacific fleet to battle.
Odd the Japanese went 4 carriers.
At Pearl and Ceylon they went 6.

Coral Sea had a say in how many carriers would be used.

 

[Garyt]

I might add that Yammamoto's late commitment of the Battleships and other forces had much to do with the fact that he was planning on ambushing the Americans - not vice-versa. It would have been a totally different scenario had the Japanese been on an even keel in intelligence (military intelligence that is). It probably would have played out a lot more like a larger scale version of Coral Sea.

Best Idea would have been to wait for Shokaku and Zuikaku, and replentish the aircraft supply on the other 4 of Kido Butai.

As the battle unfolded, it made no sense for Yammamoto to keep the other 2 forces behind the action. The Carrier force would have been better off having the Battleships up providing AA support for them.

Though it may have been doctrine - The Japanese may have thought providing AA support was not a dignified enough role for a battleship. But you would think Yammamoto who was somewhat forward thinking would have realized that this was their most effective means of employment.

 

[VBF-13]

Because the Wake operation wasn't aimed at trapping the American carriers. Operation MI had precisely that objective.

Using Midway as a submarine base makes much sense, indeed it's probably the only useful function for it, but such a function won't lead to an attack against Hawaii. You talk of resupplying carriers at Midway - where are the supplies going to come from, even for submarines? The stores have to be transported there which is exactly the point I'm making - the Japanese had tremendous difficulties keeping their isolated outposts resupplied. What was (and often still is) depicted as a red overlay covering most of the Pacific was, in reality, a series of isolated, unsupported locations that could be bypassed unless needed for strategic basing....which was exactly what the Pacific Fleet did for real.

I think I'm getting persuaded. It's those red maps, lol. I've seen them, and have hardly given them a second thought. That's right, though, most of those islands couldn't be kept sustained. And they really were of little consequence, anyway.

 

[parsifal]

Midway was about getting the Pacific fleet to battle.
Odd the Japanese went 4 carriers.
At Pearl and Ceylon they went 6.
Perhaps indicative of a larger picture.

It was. But I need to make a correction here. The overall operation did not just involve 4 carriers. it involved 8 overall, not including the seaplane carriers and seaplane cruisers that supported the operation.

The carriers involved and their air groups were:
(†) denotes killed in the operation, or for ships, sunk
(*) Reserve Aircraft (I think). insufficient or no pilots, or incomplete training


Carrier Division 1 VAdm. Nagumo Chūichi

CV Akagi†
Capt. Aoki Taijirō

CAG: 1 [1] B5N2Type 97Cdr. Fuchida Mitsuo
AVF: 18 [18] A6M2Type 0 LtCdr. Itaya Shigeru
AVB: 18 [18] D3A1Type 99LtCdr. Chihaya Takehiro
AVT: 17 [17] B5N2 Type 97 LtCdr. Murata Shigeharu
AG-6: 6 [6]* A6M2 Type 0 Lt. Kaneko Tadashi

CV Kaga†
Capt. Jisaku Okada†

CAG: 1 [1] B5N2 Type 97 LtCdr. Kusumi Tadashi†
KVF: 18 [18] A6M2 Type 0 Lt. Satō Masao
KVB: 20 [18] D3A1 Type 99 Lt. Ogawa Shōichi†
KVT: 26 [26] B5N2 Type 97 Lt. Kitajima Ichirō
AG-6: 9 [9]* A6M2 Type 0

Carrier Division 2 RAdm. Yamaguchi Tamon†

CV Hiryū† Capt. Kaku Tomeo†


CAG: 1 [1] B5N2 Type 97 Lt. Tomanga Jōichi
HVF: 18 [18] A6M2 Type 0 Lt. Mori Shigeru†
HVB: 18 [18] D3A1 Type 99 Lt. Kobayashi Michio†
HVT: 17 [17] B5N2 Type 97 Lt. Kikuchi Rokurō
AG-6: 3 [3]* A6M2 Type 0

CV Sōryū†
Capt.Yanagimoto Ryūsaku†

CAG: 1 [1] D3A1 Type 99 LtCdr. Egusa Takashige
SVF: 18 [18] A6M2 Type 0 Lt. Suganami Masaharo
SVB: 15 [15] D3A1 Type 99 Lt. Ikeda Masahiro
SVT: 18 [18] B5N2 Type 97 Lt. Abe Heijirō
SVS: 2 [1] D4Y1 Type 2
AG-6: 3 [3]* A6M2 Type 0

Attached to the Main Body

Carrier Group
Capt. Umetani Kaoru

Of the other two fleet carriers Shokaku was

CVL Hōshō
Capt. Umetani Kaoru
HVT: 8 [8] B4Y1 Type 96 Lt. Irikiin Yoshiaki (CAG)


Attached to the Midway Invasion Force


Carrier Group
Capt. Ōbayashi Sueo

CVL Zuihō
Capt. Ōbayashi Sueo

ZVF: 6 [6] A6M2 Type 0 Lt. Hidaka Moriyasu (CAG)
6 [6] A5M4 Type 96
ZVT: 12[12] B5N2 Type 97 Lt. Matsuo Kaji


Attached to the Seaplane Tender Group (not actually proper carriers)


Seaplane Tender Division 11

AV Chitose
Capt. Furukawa Tamotsu

VS: 16 [12] F1M2 Type 0 ??? (CAG)
4 [4] E13A1 Type 0

AV Kamikawa Maru
Capt. Shinoda Tarohachi

VS: 8 [8] F1M2 Type 0 ??? (CAG)
4 [4] E13A1 Type 0



Carrier Division 4 (Aleutians element of the operation)
RAdm. Kakuta Kakuji

CVL Ryūjō
Capt. Katō Tadao

RVF: 16 [9] A6M2 Type 0 Lt. Kobayashi Minoru
RVT: 20 [18] B5N1 Type 97 Lt. Yamagami M. (CAG)

CVL Junyō
Capt. Ishii Shizue

JVB: 19 [15] D3A1 Type 99 Lt. Abe Zenji
JVF: 8 [6] A6M2 Type 0 Lt. Shiga Yoshio (CAG)
AG-6:12 [7] A6M2 Type 0*

For the Indian ocean operation in April, only 5 carriers were used. I think Kaga (or it might have been Akagi) was detached to collect and finish the training of reaplacement crews, to make good some of the losses.

Shokaku and Zuikaku had participated in the Coral Sea operation, in whic about 80 aircraft had been lost. Im not sure how many crews had been recovered, but japanese SAQR services were pretty reudimentary compared to the USN efforts to save pilots. . Shokau was out of action due to battle damage, but Zuikaku only had a partial airgroup at that point. They were busily training up replacement caders....effectively the fleet carrier was acting as a trainng carrier at that point, and this gave the IJN a slight lift in pilot numbers in the following weeks and months. nothing to get too excited about, but something at least.

Shoho had been lost, with heavy loss of life, including a large proportion of its precious air group personnel. Hit by the full force of two US fleet carriers, it never stood a chance

 

[The Basket]

Zuikaku could have been at Midway. Junyo and Ryujo too.
Calling Hosho a carrier is pushing the boat out.
Typical Japanese planning. Overly complex and depends on the enemy doing exactly what you think.
Need battleships for AAA support.

A Zero from Ryujo on the Aluetians operation was the Koga Zero. so that went well.

 

[Francis marliere]

With respect, the Japanese battleships could hardly provide AAA support.

The IJN wisely estimated that AAA (at least at this stage of the war) was not effective. Ships were not expected to shoot down or deter many planes and had to steer evasively at high speed to spoil attacks. Hence distance between ships was more important the Japanese Task Forces than in other navies and ships could usually not support or be supported by other ships.

Anyway, most battleships had a pretty weak AAA at this time (usually 8 x 5"/50 DP guns and 8 x 25 mm machiune-guns cannons).


Best,

 

[Balljoint]

With respect, the Japanese battleships could hardly provide AAA support.

The IJN wisely estimated that AAA (at least at this stage of the war) was not effective. Ships were not expected to shoot down or deter many planes and had to steer evasively at high speed to spoil attacks. Hence distance between ships was more important the Japanese Task Forces than in other navies and ships could usually not support or be supported by other ships.

Anyway, most battleships had a pretty weak AAA at this time (usually 8 x 5"/50 DP guns and 8 x 25 mm machiune-guns cannons).


Best,

Right! But the battleships could have bombarded Midway rather than doing so with carrier planes. Had the IJN carriers been positioned somewhat away from Midway and tasked only with CAP and dealing with the expected US carriers, there would have been a much better chance for Japanese success. As it was the IJN carriers had to deal with Midway air attacks as well as well as the Devastators. With both bombs and torpedoes littering the hanger decks as well as overstressed CAP, the IJN carriers were overexposed and overextended.
The battleships could (and should) have shouldered the major part of the load prior to the USN carriers showing there hand.

 

[parsifal]

With respect, the Japanese battleships could hardly provide AAA support.

The IJN wisely estimated that AAA (at least at this stage of the war) was not effective. Ships were not expected to shoot down or deter many planes and had to steer evasively at high speed to spoil attacks. Hence distance between ships was more important the Japanese Task Forces than in other navies and ships could usually not support or be supported by other ships.

Anyway, most battleships had a pretty weak AAA at this time (usually 8 x 5"/50 DP guns and 8 x 25 mm machiune-guns cannons).


Best,

ah, not quite corect.

The Battlecruisers escorting the fast carriers were each equipped with 5 x 5in/40 DPs, 4 x 40mm AA and either 8 13.2mm plus 20x 25mm AA or 28 x 25mm (Ive got conflicting specifications). Yamato went into Midway carrying 12 x 5in and 34 25mm plus 4 13.2mm MG. The carriers were generally fitted with 12 5/40s and typically 24 x 25mm AA plus 22 x 13.2 AAMG

The 5/40 was an older gun than the 5/50 fitted to most of the escort destroyers. it was a reasonably effective AA gun, unlike the 5/50, which had insufficient training and elevating speeds to do this job adequately. The USN 5/38 was far superior in that regard to both guns

The Japanese made the right decision to disperse their task forces and rely on manouvre over massed defensive fire. in order to derive benefit froma mutual fire of their escorts, the Destroyers needed to be carrying an effective DP wepon, and this they simply did not possess. Whereas the 40mm Bofors could also offer some cover fire over the carrier from a normal tactical distance (about 800yards for a Destroyer, roughly 2000 yards for a Battlship) the 25mm was not really effective at those ranges.

The 25mm never was competitve to the bofors, but it was better than the 20mm fitted to most US ships in 1942.

Given the limitations of the armament, it made sense to disperse the TF when under attack and rely on manouvre over fire.

 

[tomo pauk]

With respect, the Japanese battleships could hardly provide AAA support.

The IJN wisely estimated that AAA (at least at this stage of the war) was not effective. Ships were not expected to shoot down or deter many planes and had to steer evasively at high speed to spoil attacks. Hence distance between ships was more important the Japanese Task Forces than in other navies and ships could usually not support or be supported by other ships.

Anyway, most battleships had a pretty weak AAA at this time (usually 8 x 5"/50 DP guns and 8 x 25 mm machiune-guns cannons).


Best,

The Japanese were right in the notion that their AAA was not effective. Low number of barrels, inadequate 25mm cannons, no electronics means of early warning and fire control - the Japanese BB in mid 1942 cannot put out the volume, RoF and range of the AA fire like the USN BB in mid 1942 was capable for.
In case the CVs are the only capital ships at the receiving end of a sizable air attack, not only their combing and steering away will make the deck operations as good as impossible, but even the 500 lb bombs will cause huge problems once they hit home. The BBs were less susceptible for such bombs, and, in case 1000 lb bombs are used, the CVs are doomed, BBs less so.

 

[Garyt]

but even the 500 lb bombs will cause huge problems once they hit home. The BBs were less susceptible for such bombs, and, in case 1000 lb bombs are used, the CVs are doomed, BBs less so.

A few 1000lb bombs with planes being armed/readied is a huge issue. But the carriers could take a few 1000lb bomb hits if not in the midst of conducting air operations. At both Coral Sea and Santa Cruz Japanese carriers took multiple hits of these bombs and did not sink. Needed to be repaired, yes, but sink, no. At Santa Cruz they had radar to know when to cease flight operations - at Coral see they were just luck, or lack of bad luck.

The 5/40 was an older gun than the 5/50 fitted to most of the escort destroyers. it was a reasonably effective AA gun, unlike the 5/50, which had insufficient training and elevating speeds to do this job adequately. The USN 5/38 was far superior in that regard to both guns

You know, Parsifal, the Japanese might have done better had they retained this gun for their destroyers instead of going to the 5"/50. Or at least made some modifications to the 5"/50, like turrets with better train/elevation, power ramming ability, and ability to be loaded at higher elevations.

 

[parsifal]

You know, Parsifal, the Japanese might have done better had they retained this gun for their destroyers instead of going to the 5"/50. Or at least made some modifications to the 5"/50, like turrets with better train/elevation, power ramming ability, and ability to be loaded at higher elevations.

There are other forum members who know thair guns far better than me, but from an AA defence pov, maybe. From a fleet destroyer pov, probabaly not. In the surface actions of the Solomons and after, the USN very quickly developed a very healthy respect for the Japanese fleet destroyers, who used an effective combination of 5/50 and Long Lance in the numerous small scale actions in the Solomons.

Nathun Okun had this to say about the 5/40

"The Type 89 was the first Japanese AAA weapon designed for the purpose and was used in twin mountings on most World War II warships cruiser size and larger as well as on small destroyers and some auxiliaries. The Type 89 was also used to replace many of the 12 cm/45 (4.7") AA guns on older cruisers. The Type 89 prototype was proved in 1931 and adopted for service use on 6 February 1932.
The Japanese considered the Type 89 to be a good AAA weapon and it had a fast rate of fire and excellent elevation and training speeds on the later Mods. Its primary shortcoming was a relatively low muzzle velocity and thus a short range and low AA ceiling. Used a spring rammer cocked by the recoil, similar to other Japanese AAA weapons.

These weapons were of simple construction with autofretted monobloc barrels and breech rings and used horizontal sliding breech-blocks. Total production of Type 89 guns amounted to 1,306 guns, with 836 being manufactured between 1941 and 1945. Of these, 362 were mounted ashore, including 96 in the Yokosuka area and 54 in the Kure area".

He has this to say about the 5/50

"These weapons were used on most Japanese destroyers built between 1926 and 1945 in both single and twin mounts. The mountings for these guns were a revolutionary design, as the Japanese were the first to use weather and splinter-proof mounts on destroyers. The second batch of these destroyers were also the first to use medium caliber guns with high elevations, giving them a DP function. However, the very slow training speeds and lack of power ramming made these mountings almost useless against the fast-moving aircraft of World War II.
These weapons were of built-up construction, originally three layers (Model No. I) and later two layers (Model No. I2) along with the usual breech ring and breech bush. About 700 guns were manufactured. Surprisingly for this size weapon, these guns fired bag ammunition and used a Welin breech-block".

Surprisingly perhaps, the HAA armament remained the primary area defence weapons even over the Bofors for the entire war, because of their range and burst radius. Because of this, and the overall ascendance of aircraft as the primary attacking weapon system, the USN 5/38, despite its rather poor anti surface capability, was probably the best destroyer weapon of the war.

 

[Garyt]

There are other forum members who know thair guns far better than me, but from an AA defence pov, maybe. From a fleet destroyer pov, probabaly not. In the surface actions of the Solomons and after, the USN very quickly developed a very healthy respect for the Japanese fleet destroyers, who used an effective combination of 5/50 and Long Lance in the numerous small scale actions in the Solomons.

The 5"/50 was a pretty good surface weapon, but had a low rate of fire compared to the 5"40. If the 5"40 was used for surface work it would have had a better ROF, though abut 75% of the range. As Destroyers used more common shells than anything, and muzzle velocity does not effect HE type shells penetration really, it would have done OK from that aspect as well.

The 10cm type 98 would have been good I would think - very high rate of fire, equivalent ROF to the 5"/38. Not sure how effective it would be vs ships, but a great aa weapon. Armed like this they would have made great carrier escorts.

The 25mm never was competitve to the bofors, but it was better than the 20mm fitted to most US ships in 1942.

The Oerlikon was a heck of a lot better than the Japanese 25mm. Biggest issue was ROF - 300 or so practical for the Oerlikon, the 25mm was held down to about 115 per minute due to have to replace magazines. They also were relatively slow on traiining and elevation,and apparently had excessive muzzle blast, more of an issue with the trip-mounts.

The US 1.1" weapon (28mm) was somewhat subpar. Low ROF (practical about 100) was the biggest issue with this weapon. These were rpelaced with Oerlikons as quickly as possible.

the USN 5/38, despite its rather poor anti surface capability, was probably the best destroyer weapon of the war.

I don't know how "bad" it was at surface work. It had a good ROF, about 1.5x that of the Japanese 5", fored a heavier projectile with a heavier bursting charge. And AP rounds on destroyers did not make a lot of sense - they did not need them to defeat destroyers or smaller armour, and many cruisers had armor that could not be defeated by a 5" shell even if AP. And forget trying to pierce a Battleship with a 5" AP projectile. That's why destroyer rounds were some form of common, special common or HE.

The only thing the 5"/38 lacked in was range, having about 75% of the 5"50's range. I think what made a difference for the Japanese and help make up for their slower rate of fire - their destroyers were larger, and had mostly dual mounted 5 inchers, the US had single mounts for the most part.

So a US destroyer might have had 4-5 5"/38's, the Japanese destroyers often had 6-8 of the 5"/50's. Plus the Japanese destroyers were about 150% of the tonnage of the US ones.

 

[parsifal]

The Japanese considered it to be an exceelent weapon, but as you point out, compared to the oerlikan, it had a slower rof due to the magazine feed.

The 25mm was somewhere between the bofors and the oerlikan in terms of performance. A quick look at what it could do revelas the following

Elevation With 0.55 lbs. (0.25 kg) HE Shell -10 / +85 degrees
Range @ 45 degrees 7,439 yards (6,800 m)
Range @ 50 degrees 8,200 yards (7,500 m)
AA Ceiling @ 85 degrees Effective: 9,843 feet (3,000 m)
Maximum: 18,040 feet (5,500 m)
Rate Of Fire Cyclic: 220 - 260 rounds per minute
Effective: 110 - 120 rounds per minute

Its ammunition had the following characterisitcs

The oerlikan had a much rof, but both its bursting charges and effective ranges were far less than the Japanese gun. both guns were obsolete by 1945 b against fast moving aircraft, but the oerlikan, in my opinion was moreso.

Its range characteristics were as follows

Elevation With 0.271 lbs. (0.123 kg) HE-I Mark 3 Shells
Range @ 10 degrees 3,450 yards (3,154 m)
Range @ 15 degrees 3,950 yards (3,612 m)
Range @ 20 degrees 4,275 yards (3,909 m)
Range @ 25 degrees 4,525 yards (4,138 m)
Range @ 30 degrees 4,650 yards (4,252 m)
Range @ 35 degrees 4,725 yards (4,320 m)
Range @ 40 degrees 4,775 yards (4,366 m)
Range @ 45 degrees 4,800 yards (4,389 m)
AA Ceiling 10,000 feet (3,048 m)
These however are theoretical ballistics ranges Effective range during World War II against aircraft for manually aimed weapons rarely exceeded 1,000 yards (910 m), although USN Oerlikon gunners were expected to open fire at 1,200 or 1,300 yards (1,100 or 1,200 m) which allowed aiming corrections by the point the target entered effective range. This was far too late to be considered effeective against an aircraft travelling at 350mph or more. An aircraft travelling at that speed would be over your position in just over 5 seconds. Against a Kamikaze, the 20mm shell was simply not big enough to stop anything in that time frame. The Japanese didnt have to contend with kamikazes so, the playiong field is not level in this comparison. Effective range of the 25mm was about 2000 yds and that made all the difference. still inadequate, but better than the oerlikon

The rof of for the oerlikan was far superior to the 25mm

Rate Of Fire
Cyclic: 450 rounds per minute
Practical: Between 250 to 320 rounds per minute

However the type still was affected by the magazine feed, which did downgrade performance by an amount I cannot fully determine

According to nathun Okun .....

Between December 1941 and September 1944, 32% of all Japanese aircraft downed by the USN were credited to this weapon, with the high point being 48.3% for the second half of 1942. In 1943 the revolutionary Mark 14 Gunsight was introduced which made these guns even more effective. This gunsight was developed by Dr. Charles Draper of MIT, who calculated that since the guns fired at relatively short ranges, a crude but simple and effective relative-bearing system could be used to control these weapons. The Mark 14 gunsight used two gyros to measure vertical and lateral rate of change, calculated the lead angle to the target aircraft and then projected an off-set aiming point for the gunner. Use of the Mark 14 did require that an electric power connection be provided to the formerly free-standing mountings. This gunsight was later adopted as part of the Mark 51 director which was used to control the 40 mm Bofors, greatly increasing their effectiveness. See the Technical Board essay on the Mark 51 director for additional information. Postwar, the Mark 14 was replaced by the Mark 20 Gun Sight, which was a lighter, simpler design. The Mark 20 was ready to use in ten seconds after being switched on while the Mark 14 took three minutes.

In 1944-45, the USN found that 20 mm shells were too light to stop Japanese Kamikaze planes and the higher approach speeds of these planes made manually controlled guns obsolete. As a result, Oerlikons were replaced by 40 mm Bofors where ever possible during 1944-45 and removed entirely from most US ships by the mid-1950s.

During the war, the USN greatly increased the numbers of 20mm mounts fitted to their ships. This was achieved by replacing the single mounts with the new twin mount, from 1944. this was a definite mistake. It was iplemented in an effort to reduce top weight . The Mark 24 twin mounting was deliberately designed such that it could be installed on the same foundation and with the same working circle as a single mount. On a comparative weight basis, three twins could replace four singles, thus gaining two barrels while saving four crewmembers. However, an SCB analysis tentatively concluded that these three twins were only effective as the four singles, as the increased noise, smoke and vibration of the twin mount reduced the effectiveness of the Mark 14 gunsight.

 

[Garyt]

The Japanese considered it to be an exceelent weapon, but as you point out, compared to the oerlikan, it had a slower rof due to the magazine feed.

Maybe the Brass thought that early in the war, but here is what the Japanese thought of this weapon:

4) According to US Naval Technical Mission to Japan report O-47(N)-2, the Japanese saw the following deficiencies in these mountings in decreasing order of seriousness:
a) The multiple mounts could not be trained and elevated rapidly enough, either by power or manual drive.
b) The gunsights were inadequate against high speed aircraft.
c) The guns had excessive vibration, making them difficult to keep on target.
d) The capacity of the ammunition supply equipment was inadequate, causing interrupted fire and a greatly reduced operating routine.
e) The muzzle blast caused problems for both the guncrew and equipment.

Actually, the US gun that the Japanese 25mm most mirrors is the US 1.1". Similar rate of fire, larger shells. It even had faster train and elevation speeds than the Japanese 25mm. The US 1.1" was phased out quickly and replaced by the Oerlikon 20mm. And actually the Oerlikon as you pointed out was credited with a high percentage of AA kills. It was not the ideal weapon for the kamikaze, but few weapons were ideal, and the kamikaze was a very unusual type of attack.

Actually, the Navweaps site has this regarding the Japanese 25mm:

The 25 mm Type 96 was widely used throughout the Japanese Navy with about 33,000 guns being produced. The Japanese considered this gun to be an excellent weapon, but it did not compare well to either the Bofors 40 mm or the Oerlikon 20 mm weapons used by the Allies. The magazines for the Type 96 held only 15 rounds, so frequent stoppages for change outs were required.

However, an SCB analysis tentatively concluded that these three twins were only effective as the four singles, as the increased noise, smoke and vibration of the twin mount reduced the effectiveness of the Mark 14 gunsight.

Interesting. This is one of the primary complaints on the 25mm, and it was more of a problem on the triple mount. I think multiple gun mountings were the bane of many WW2 anti-aircraft autocannon.

Also with the range of the lighter WW2 autocannons - I think range is overrated to a point. The reason why is that the further the range, the lesser chance of a hit. And I'd also think that a weapon with say a 2,000 meter range has a better chance of hitting at 3/4 of it's range (1500m) than a longer range weapon has at hitting at 3/4 of it's max effective range, i.e. a 4,000 meter range gun hitting at 3,000 meters.

So a longer range weapon means more seconds on target. But the seconds gained at the extremes of range are far less important than the seconds on target at say 1/2 range or closer.