Battleship Accuracy

While going through old posts and comments, I came across the following comment from ‘Ray D’ [1] about battleship accuracy in a post about battleship and carrier throw weights (see, “Carrierand Battleship Throw Weights”).  He’s responding to a comment that denigrated the accuracy of a battleship’s big guns.  The comment is so interesting that it deserves a post of its own for wider dissemination since not everyone reads all the comments. 
 
Note:  I have no way to verify the accuracy of the reader’s comment but I have no reason to doubt it, either.  I have not seen either of the two referenced reports/sources.  You can assess the validity for yourself.
 
I’ve copied his comment with just a couple of minor changes for grammar and readability.
 
In the comment, the author makes the distinction between precision and accuracy.  Some readers may not be familiar with the distinction so here’s the difference.  Precision is the grouping of several shots from a gun.  The tighter the grouping, the better the precision.  However, a tight grouping (high precision) does not necessarily mean good accuracy.  Accuracy is how close to the intended target the shot is.  Precision is how tight the grouping is regardless of the accuracy.  A series of shots may have very good precision (tight grouping) but very poor accuracy (a tight group that’s way off the target).  Conversely, the accuracy could be good but the precision might be poor.
 
The statement the reader is responding to declared the following about a battleship’s accuracy.
 
"estimated accuracy of 2.7% at max range"
 
The reader’s response was the following:
 

With all respect (and I mean a lot of respect), this comes from probably the most misrepresented report about US Navy WW2 era equipment of all time and the claim ignores the myriad of patently ridiculous assumptions that the report made about the hypothetical target given exactly what naval targets existed at the time.
 
To keep it short, their assumed target was a mythical Iowa-class counterpart that was performing rapid evasive maneuvers and somehow NEVER dropped below its assumed maximum speed of 35.4 knots.
I hope it doesn't need to be explained that this was and is physically impossible!
 
Furthermore, the only Battleships in the world (ever) that were capable of performing such radical evasive maneuvers and maintaining a targeting solution of their own were American; all others would have had to either choose shooting or evading due to their lack of stable verticals; so in real terms the report itself is entirely worthless unless the US Navy was expecting to fight the US Navy.
 
Against a Yamato acting according to Japanese doctrine, ergo attempting to maximize its own gunfire efficiency, the predicted accuracy for the Americans would be closer to 8% at that range, or over three times higher.
 
That aside, in the context of shore bombardment this entire argument is disingenuous and built around an obvious categorical error: at the last I checked, most strategic military targets such as bases, ports, airfields, factories, and governmental offices do not in fact move.
 
So, instead of accuracy assumption against moving targets, it's better to speak of the raw dispersion values of the guns in question.
 
According to live combat data taken from WW2 and Korea, the Iowa-class Battleships during those periods had range errors of only 0.6% of range, or 254yds at their maximum range of 42,345yds, making them the most accurate battleships to ever be built even then. Deflection error was usually negligible in comparison, as range error is always the larger number.
 
Of course, that's just the WW2 figures. Just by the 1980s reactivations advancements made to fire control and propellants saw a ~29% decrease in dispersion, again drawn from live combat data. During firing trials, the USS Iowa produced a range error of 0.3% of range (or ~127yds at maximum).
 
To put this in context, the blast effect of the Mk14 HC shell was significant enough that it was reported to incapacitate infantry within 500yds, defoliate trees within 300yds, kill exposed infantry within 250yds, level trees and light structures within 200yds (also destroy most aircraft), and even destroy MBTs within 100yds. This is roughly comparable to a WW2 era 2000lb bomb (or a modern 1000lb bomb).
 
Or, in other words, the USS Iowa during the mid-1980s had a greater than 50% chance of destroying a tank at 42,345 yards with a single shell; or if it fired all 9 guns at the same target, greater than a 99.987003826% chance.
 
By all measures that was absolutely excellent accuracy, even if the guns were not as precise as one may desire.  That's just with 1980s technology.  Today, since you already would have to make all new guns and the ships to carry them, you could utilize developments such as Polygonal Rifling and ETC cannons to not only further increase the accuracy of the guns, but decrease time of flight or drastically increase the effective range of the guns well beyond 50 nmi without sacrificing payload; and that's without using science-fiction technology such as rail guns. Of course, it goes without saying that guided 16in shells would be essentially child's play to develop as well, considering they did it with the 8in MCLWG program to great success in the '80s.
 
But I digress, my point was that the Iowa's guns in their final configurations were accurate enough for all targets they were within range of. They were imprecise, yes, but VERY accurate.

 
I have nothing to add to this other than it further illustrates the amazing capabilities of the US battleship.
 
 
_____________________________

 
[1]Ray D.May 12, 2023 at 10:37 PM
https://navy-matters.blogspot.com/2023/05/carrier-and-battleship-throw-weights.html?showComment=1683956277384#c8102893492469470189

Naval Gun Accuracy

It’s discouraging to see how many people believe that modern fire control systems guarantee unerring accuracy.  I’ve seen claims that the Oto Melara 76 mm only needs three rounds per engagement against anti-ship missiles.  That’s absurd!  When the head of Oto Melara, in a live fire test, agrees to stand on a target protected by one of his guns that has only three rounds in the magazine, I’ll begin to believe the claim.
 
So many people seem to think that modern guns can’t miss.  I guess this is an example of a little bit of knowledge being a dangerous thing.  People understand just enough about computers to know that we can write a program that predicts where a round should go to impact/intercept the target and they assume that the program can’t be wrong, therefore, the shot must hit with unfailing accuracy. 
 
Reality, however, is much different.  Yes, a program can make a prediction – that’s just simple mathematics and that’s child’s play.  What the program can’t do is account for the hundreds of factors that actually affect the accuracy of a naval gun.  Let’s briefly consider some of the more obvious factors:
 
Stabilization – One of the most blatantly incorrect beliefs among naval observers is the myth of stabilization.  People forget that both the firing platform and the target are continuously pitching and rolling, among other movements.  Yes, we have stabilization (of the firing platform, not the target!) but stabilization is not even remotely perfect.  The guns are large, heavy chunks of steel and have inertia.  Just because the stabilizer computer signals the gun to move doesn’t mean it can instantaneously accomplish that movement.  There is a lag and in the world of micro-deviations (we’ll address that shortly), which is what we’re discussing, that’s a problem.  Stabilization is a gross phenomenon, not a micro phenomenon and it does not, indeed cannot, assure accuracy – it just reduces gross inaccuracy.
 
Let’s consider some other common factors that impact accuracy:
 

• Barrel Wear – wear is a constantly changing phenomenon and is not uniform along the length of the barrel
• Barrel Temperature – changes on every shot and is not uniform along the length of the barrel
• Wind – constantly changing and changing throughout the length/time of the shell’s flight profile
• Barrel Movement – the barrel is moving (pitching, rolling, and attempting to stabilize) while the round is traveling through it!
• Shell Uniformity – every round has minute (and no so minute!) differences in weight, shape, smoothness, dents, etc. and each one affects accuracy
• Friction – this is a factor of the shape of the round, density of the air, humidity, wind, etc. and, of course, there’s always friction between the barrel and the shell
• Humidity – this is constantly changing on the micro scale as the shell encounters wind currents, spray, fog, rain, etc.
• Density – the density of the air is constantly changing due to temperature, humidity, altitude, etc. causing changes in friction and speed of the projectile
• Temperature – changes with elevation, wind currents, and wave behavior causing updrafts and downdrafts
• Target Movement – the target is constantly moving in all three dimensions while the intercepting shell is being fired and traveling through the barrel and the target continues to move during the entire travel time of intercepting shell;  some of the movement is due to physical factors (wind, friction, etc.) and some is due to intentional terminal maneuvering;  when we take a radar ‘fix’ on the target, the implicit assumption is that the target will continue on its path and that’s utterly false, as we just noted

 
What program has the slightest hope of accurately modeling those factors especially since we have no means of measuring most of them other than in the grossest sense?
 
 
Deviations
 
So, we’ve now acknowledged that there are too many factors that impact accuracy for us to account for all of them and we lack the sensors to do so even if we could program them into the fire control algorithm.  But, you say, the deviations are minor.  Well, let’s examine the magnitude of the effect of the cumulative ‘minor’ deviations.
 
Projecting a straight line from the shell in the barrel, waiting to be fired, to the predicted intercept point, gives us a travel path that we think/hope will meet the target.  Any deviation will cause an angular change from the predicted travel path.  That angular deviation can be considered in degrees.  If the shell perfectly follows the predicted path, that would be 0 degrees deviation.  If the shell were to, ridiculously, take an immediate right angle turn off the predicted path, that would be a 90 degree deviation.  Realistically, the deviation will be on the order of 0-10 degrees or so.  Let’s see what impact small degrees of deviation have on the difference between the actual intercept point as compared to the predicted point.
 
For this illustrative example, let’s consider a predicted intercept point at a distance of 1 mile (5,280 feet).  We’ll use the geometry of a right triangle to calculate the deviation.  Specifically, we’ll use the formula
 
     tan(deviation angle) = opposite/adjacent
 
rearranging,
 
     opposite = tan(deviation angle) * adjacent
 
where,
 
opposite = the deviation from theoretical intercept point, in feet
adjacent = 5,280 ft  (distance to theoretical intercept point)
deviation angle = the angular deviation from the predicted intercept path, in degrees
 
Using the above formula, we get the following results for various degrees of deviation.
 
10 deg = 931 ft
5 deg = 462 ft
1 deg = 92 ft
0.5 deg = 46 ft
0.1 deg = 9 ft
 
We see then that even a miniscule 0.5 deg deviation will result in a 46 ft miss.  We have to be down around 0.1 deg or less deviation to hit our predicted intercept point close enough to be effective.  Of course, that assumes the target perfectly followed its predicted travel path and didn’t change course, altitude, or speed!
 
Wow!  That is not much allowable deviation before we have a clean miss!  From observations of video of live fire gun exercises, my estimate is that deviations of 0.5-5 degrees are normal.  That’s not encouraging.  I’m beginning to think that hitting a target with a naval gun is almost impossible.
 
Before we throw up our hands and give up trying to hit an intercept point with a naval gun, let’s recall that there are a few things that can help improve our odds.
 
Number of Shells – It’s a given that every shot we fire will have a deviation to some extent.  However, if we fire enough shells toward the predicted intercept point, one or some of them will, statistically, wind up being close enough to be effective.  This argues for smaller caliber projectiles that can be fired quickly and in large numbers.
 
Rate of Fire – This is another way of saying, number of shells, but it goes beyond that.  There’s a time lag between every shot and the greater the time lag, the fewer shells we can put into the predicted intercept point.  To illustrate, if we could fire a thousand shells in one second, we’d saturate the intercept point and compensate for the individual inaccuracies with numbers.  On the other hand, if we can only fire one shell per minute, then we can only ever have one shell in the intercept area at a time before the intercept point changes significantly and odds are it will miss due to the various factors we’ve discussed.  This argues for extremely high rates of fire.
 
Stabilization – The quicker our gun can respond to stabilization commands, the more accurate we’ll be.  This is accomplished by decreasing the inertia of the gun which is accomplished by decreasing the weight of the gun and/or increasing the power of the train/elevation motors.  This argues for smaller, lighter weight guns.
 
We see, now, why a 5” gun is very unlikely to be effective at hitting a cruise missile.  In fact, modern 5” guns have been proven to be woefully inaccurate even against slow moving (relative to a missile) Boghammer boats (the Vincennes incident).
 
Fragmentation - Yet another compensating measure is fragmentation.  If we have to have a direct hit on the target to kill it, our odds are extremely poor.  However, if we can just be in the general vicinity of the target and kill it via shrapnel (fragmentation), our odds increase.  The larger the effective fragmentation area, the better our chances.  This suggests using large shells that can disperse large quantities of shrapnel.  However, there is a limit because the fragmentation pattern takes time to spread out after the shell explodes and if too much time is taken the target has flown past before the shrapnel can spread out.  So, there’s an effective limit on how big a pattern can be effectively used but I have no idea what that limit is.
 
Guidance – Guided projectiles offer another way to improve accuracy but at a significant, literal cost.  There are companies who offer, or are developing, small guided projectiles but, as far as I know, there is no test data under remotely realistic conditions that demonstrates that they are effective.  They may or may not be.
 
 
Conclusion
 
It is clear that naval guns are inherently inaccurate.  For the case of fixed land targets, we can compensate for inaccuracy with explosiveness.  If we’re firing 16” battleship shells, accuracy is a lesser concern as the giant 50 foot craters will compensate for a lot a inaccuracy.  We can also substitute multiple salvos for accuracy knowing that statistical odds will ensure that if we fire enough rounds, some will hit the target.  Besides, it’s not as if a fixed target is going anywhere.
 
However, if we’re trying to shoot down an anti-ship missile, we need small, light, very rapid fire guns which is the concept behind 20-30 mm CIWS guns.  It’s clear that larger guns (5”, 57/76 mm) are ineffective for the anti-air role, barring dumb luck.

Guns Or Missiles?

One of the lamentable tendencies exhibited by naval observers and commenters is to evaluate weapons in isolation.  I’ve preached about the dangers of this yet it still happens all too frequently.  For example, if one considers the use of offensive missiles versus large caliber naval guns, the discussion invariably becomes a one-versus-one comparison - a single missile’s properties versus those of a single shell.  People will cite range or speed or explosiveness or whatever supports their favored weapon.  However, that kind of comparison and evaluation is always incomplete and always wrong.  Consider the following example.
 
An enemy’s island base needs to be destroyed.  How do we do it?  The obvious answer is we stand off a thousand miles and launch cruise missiles at it.  The less obvious but likely more realistic answer is that we used up most of our cruise missile inventory in the first month of the war and we, essentially, have none left and our industry, which is geared towards a peacetime production of a hundred missiles per year, can’t even begin to supply replacements in any useful quantities and what few we get are reserved for only the very highest priority targets.  Now what do we do? 
 
We could place a carrier in harm’s way and try an air strike, however, the island base is heavily defended by SAM batteries so we’ll suffer aircraft losses that our industry can’t replace in any useful time frame.
 
We could have the Air Force try a bomber strike but the enemy destroyed our only base in the region on the first day of the war and our handful of flyable bombers are tasked with much higher priority missions.
 
Hmm …   Now what?
 
Well, if we had ships with large caliber naval guns we could just sail up to the island and erase it from existence.  Of course, the tactical situation would have to be appropriate but that’s always the case for any mission.
 
Thus, a missile might have more desirable properties but the correct answer is more likely large caliber naval guns when one considers the larger picture of the overall war, munitions inventory, and replacement cost and time frames.
 
This also illustrates another guiding principle and that is flexibility.  Again, so many people debate weapon systems as mutually exclusive, one or the other, instead of acknowledging that there is a need for multiple options instead of one, exclusive choice.  It’s better to have options and not need them then to need them and not have them.  Options give us flexibility.  When we lose our only useful base, when our industry can’t supply replacement munitions, when industry can’t replace aircraft losses, when the enemy upsets our plans, flexibility gives us the ability to stay in the fight.

USS Boston CAG-1
Guns or Missiles?  Both!
Note two forward triple 8" mounts and aft missile launcher.

Keep this in mind as your discuss (let’s be honest … as you argue) weapon systems.  The ‘correct’ answer is almost always ‘both’ and it’s quite likely that the less advanced system will turn out to be the preferred choice for reasons other than pure performance specifications.
 
Guns or missiles?  The Navy has unwisely selected only missiles when the correct answer is both! 

Naval Guns on Smaller Vessels

The Navy, today, seems to have a fascination with small guns – the smaller the better, it seems.  The Constellation FFG, for example, has an incredibly small gun given the size and role of the ship.  Following is a table of some smaller ships and the guns they carried.  The list is sorted by gun size.  It’s illuminating, to say the least.

 

Note that the Constellation FFG, despite being the largest ship listed by a significant margin has the smallest gun.  Also, note that the two most modern ships in the list are also the two lightest armed.

 

 

 

Ship Type	Ship Length, ft	Gun(s)	Gun Range, yds
Knox Class FFG	438	1x 5” (127mm)	25,000
Landing Craft LSM(R)	203	1x 5” (127mm)	17,500
Flower Class Corvette	205	1x 4” (102mm)	13,850
Perry Class FFG	453	1x 3” (76mm)	20,122
Harris Class APA	435	4x 3” (76mm)	14,600
Buckley Class DE	306	3x 3” (76mm)	14,600
Gato Class Submarine	311	1x 3” (76mm)	14,600
Pegasus Class PHM	133	1x 3” (76mm)	20,122
LCS - Freedom	378	1x 2” (57mm)	19,000
LCS - Independence	418	1x 2” (57mm)	19,000
Constellation FFG	496	1x 2” (57mm)	19,000

 

 

Naval guns are no longer considered main weapons but still …  this is embarrassing.  If this trend keeps up, it won’t be long before our main naval gun will be a guy with a pistol sitting in a lawn chair on the bow.  Or, maybe we’ll upgrade to a dual mount with two guys sitting side by side?

Naval Bombardment Philosophy Recap

Well, our discussion wandered off into a land artillery discussion which is, admittedly, more than a bit related to naval bombardment.  The upshot of the discussion seemed to be that there are good reasons for the semi-standardization of land artillery on 155 mm guns.  The reasons include logistics, cost of the gun, ease of movement of the guns/munitions, munitions inventory, and general applicability/effectiveness of the 155 mm caliber.

I would note that most of those reasons don’t apply to naval guns in any significant way.  The cost of the naval gun is small compared to the overall cost of the ship, movement is effortless since the ship moves anyway, logistics are no more of a burden/challenge than for any other aspect of the ship’s logistical needs, and ships have relatively large magazines and sufficient inventory of munitions for their mission needs.

Beyond that, naval guns have a few advantages over land.  Modern naval gun loading is largely or totally automated which allows the rate of fire to be maintained indefinitely as opposed to hand loaded land artillery.  This allows the extended operation of larger caliber guns, if desired.  Being on ships, naval guns are inherently more survivable due to ‘stealth’, continual movement, and armor (well, guns used to be in armored mounts and ought to be today).

The conclusion seems to be that land artillery has settled on a reasonable compromise in the 155 mm gun but that naval guns are not bound by the same limitations.  Therefore, there is no reason not to have larger caliber naval guns.  Larger caliber guns produce bigger ‘booms’ and that is generally good.  For those cases where bigger is not better, ships, both individually and as a fleet, traditionally have a range of gun sizes and can choose the appropriate size. 

As with most things, a range of naval guns offers the best overall performance and value.  Too many people want to argue for one-or-the-other options when a mix is almost always best.  I don’t think anyone would argue that there are times when having a 16” gun available is highly desirable but that doesn’t mean the entire fleet should be armed with them.  A fleet mix of 5”, 8”, and 16” would seem reasonable. 

Some commenters have made the case for naval 155 mm guns and that’s a fair discussion.  Whether the benefits of moving to that size would be worth the disruption of the current 5” logistics, training, and support train is debatable.

In short, nothing about land artillery experience precludes larger caliber naval guns and I see no reason why they should not be part of the fleet gun mix.

Naval Bombardment Philosophy

Current US Navy gun support for amphibious landings has a capability gap – we have none!  The question is, is that due to a belief that naval bombardment as a vital element of an amphibious assault is not needed or is it due to mere neglect and stupidity?  In other words, is our utter lack of gun support due to philosophy or neglect?  One would be tempted to say that it must be due to neglect because the value of naval bombardment is so incontestable as to be self-evident.  However, historically, this has not always been the case.  Naval bombardment has not always been seen as necessary for the success of an amphibious assault.

The largest amphibious assault in history, Normandy, employed only brief and perfunctory pre-assault bombardment that was intended only to suppress the defenses, not destroy them. (2)  Contrast that to the Pacific assaults on Iwo Jima and Okinawa where the Navy conducted non-stop bombardments for weeks prior to the actual assault.  There you have the two extremes – nearly none and almost unlimited.  Which philosophy is right?  They can’t both be right, can they?  Let’s look a bit closer at the historical basis for the two different philosophies and, with that understanding, try to assess our current naval bombardment needs, if any.

As noted by historian and former naval amphibious planner, Christopher Yung, in his book “Gators of Neptune (1), which documented the naval amphibious planning for Normandy,

Another point of departure with Pacific amphibious doctrine was the Mediterranean view of the purpose, effectiveness, and duration of a naval bombardment of coastal defenses just before an amphibious assault.  Admiral Cunningham [Command in Chief, Mediterranean Fleet, First Sea Lord] … stated that, “the Americans in the Pacific placed a high value on naval bombardment in support of amphibious assaults, particularly by battleships, much higher than I thought was really justifiable.” (1, p.38)

However, Yung further notes that Admiral Cunningham changed his mind.

Following the war, Cunningham felt he should have given greater credence to the value of naval gunfire support for an amphibious landing … (1, p.38)

Based on their experience with various Mediterranean assaults, the US Army believed that pre-assault bombardment served only to alert the enemy and ruin the element of surprise. (1, p.38)  The Royal Navy’s RAdm. L.E.H. Maund seconded this philosophy but ascribed it to the British military’s deficient resources. (1, p.39)  We see in this thinking the belief, potentially correct, that if the attackers have less than overwhelming force that the element of surprise may be more important than pre-assault destruction.  Of course, one could ask why anyone would attempt an amphibious assault with less than overwhelming force but that’s a separate issue.

Supporting this minimal bombardment belief was British data on artillery effectiveness against hardened defenses which led the British to conclude that naval gunfire could, at best, provide suppressing fire which might temporarily neutralize the defenses but would be ineffective at destroying them. (1, p.39) It should be noted, however, that there is a world of difference between artillery fire and very larger caliber battleship and heavy cruiser fire with up to 16” guns.  The British did not appear to take that difference into consideration.

Yung notes, however, that this ‘Mediterranean’ minimal bombardment philosophy was not unanimous.  VAdm. Hewitt (commander US naval forces, Mediterranean) noted that pre-assault bombardment was an essential precursor for a successful assault. (1, p.39)

It is also noteworthy that the Mediterranean philosophy was derived from early war experience with less accurate and less lethal artillery and naval guns.  As the war went on, naval gunfire accuracy and lethality improved immensely

Eisenhower, himself, weighed in on the value of naval bombardment, stating that,

Pre-assault and support naval gunfire on beach defenses and pre-arranged targets was so devastating in its effectiveness as to dispose finally of any doubts that naval guns are suitable for shore bombardment. (1, p.39)

His thoughts did not, however, wind up dictating the extent of the Normandy pre-assault bombardment which was, by Pacific standards, minimal, at best.

RAdm. Hall (Commander, 11^th PHIBFOR, Force Omaha), expressed his dissatisfaction with the pre-assault bombardment after the Normandy operation was over.

It is believed that the time available for pre-landing bombardment was not sufficient.  German defensive positions were well camouflaged and strong.  It is considered that these positions should be destroyed by slow aimed fire from close range prior to the landing.  Something more than temporary neutralization is required when troops face beach mines, wire, anti-tank ditches and similar obstacles after landing. (1, p.208)

Note Hall’s call for close range naval fire (enhanced accuracy) as opposed to standoff fire (reduced accuracy).  As it happened, there were instances of individual destroyer Captains, on their own initiative and in violation of planning, moving their ships very close in to provide effective and critical point-blank gunfire.  This illustrates the element of risk in effective naval bombardment and the acceptance of that risk in order to achieve objectives.  Contrast this with today’s exceedingly risk averse Navy culture!

In contrast to Hall’s deprecating view of the bombardment effort, Adm. Ramsay (Allied Naval Commander, Expeditionary Force) thought the minimal pre-bombardment was adequate and justified.

That naval gunfire neutralizes rather than destroys is still considered to be true … the policy of beach drenching [ed. short term suppressive fire] has been fully justified. (1, p.208)

Ramsay, then, believed it preferable to momentarily neutralize (suppress) enemy defenses rather than put any great effort into destroying them.

In the actual event, post-assault observation and analysis indicated that relatively few fortifications, gun housings, and casemates were outright destroyed.  This should come as no surprise given the inaccuracy of fire control at that time and the minimal amount of time the bombardments were conducted.  Pacific experience differed greatly.

The use of high velocity guns at [Kwajalein] showed, at least according to the US Navy, that this weaponry could be effective at smashing concrete pillboxes. (1, p.77)

As the Army noted, pre-assault bombardment does, indeed, notify the enemy of the coming assault.  At that point, it becomes a race between the attackers getting sufficient force ashore to achieve their objectives and the defenders getting sufficient reinforcements to the area to ward off the assault.  For Normandy, where the potential pool of reinforcement was vast, it was feared that a prolonged pre-assault bombardment might have allowed the Germans time to reinforce beyond the point that the assault force could overcome.  In contrast, in the Pacific, the Japanese forces on a given island had no source of reinforcement.  Hence, losing the element of surprise was irrelevant – the defenders couldn’t reinforce and couldn’t leave.  They were fixed and isolated and every additional hour of bombardment meant fewer and less effective defenders and defenses.

Naval Bombardment

While the concept of minimizing pre-assault bombardment in order to minimize the enemy’s time for reaction and reinforcement has some surface appeal and, indeed, logic behind it, the larger driving force of overwhelming force ought to negate the concept.  If one has overwhelming force (and if you don’t, why are you attempting the assault?) then the enemy’s reinforcement efforts can be interdicted with air power, airborne infantry, and long range battleship gunfire.  This presents the best of all worlds: extensive pre-assault bombardment reduces the immediate enemy defenses and the overwhelming force interdicts the reinforcement effort.  Thus, both the immediate defenses and the reinforcements are attrited before the actual landing occurs.  To a large extent, interdiction of reinforcements actually occurred at Normandy, thanks to overwhelming force, although the interdiction was divorced from an extensive pre-assault bombardment.

The British view that the element of surprise was necessary to make up for a lack of resources – meaning, a less than overwhelming assault force – was not an issue for the Americans in the Pacific as every US assault did involve overwhelming force.  Thus, surprise was, again, irrelevant.

In contrast to the Mediterranean view that bombardment was ineffective at destroying defenses, Pacific bombardments did achieve the objective of forcing the Japanese to concede the actual landing and retreat to inland prepared defenses in the form of caves, tunnels, and other fortifications that could be hidden from easy observation and protected from heavy bombardment.  Shore defenses were, in fact, found to be susceptible to prolonged bombardment, hence, the relocation of the defending assets to inland locations.

From the preceding discussion we see, then, the tension between the two conflicting philosophies:

• The desire to maintain the element of surprise
• The desire to inflict as much pre-assault destruction on the enemy as possible

While both philosophies offer seemingly valid arguments and rationales, it appears that the Mediterranean philosophy of minimal bombardment is largely based on assault force shortcomings and failings such as the lack of overwhelming force, limited resources, and doctrinally ineffective application of naval gunfire.  Thus, for a properly resourced amphibious assault the Pacific practice of prolonged pre-bombardment would appear to be the correct choice.

Having examined the issue of pre-assault bombardment, it is important to note that the discussion has nothing to do with bombardment support during and immediately after the assault landing.  Regardless of whether the assault used minimal or maximum pre-assault bombardment there is an undisputed need for naval gun support during the actual landing and immediately after, until the landing force can get their own artillery ashore and operating.

How does all this impact our views on naval gunfire today?  As you might expect, the exact same considerations and conclusions about pre-assault bombardment still apply.  However, technology has introduced some modifications into the methodology:

Range – Today’s defenders can use cruise and ballistic missiles with ranges of hundreds or thousands of miles.  Even modern artillery and rocket launchers have ranges of many dozens of miles.  Thus, bombardment must not be limited to the immediate landing area but must take into account defending ‘batteries’ located hundreds of miles away.  These remote targets may need to be serviced by air power rather than naval guns but, regardless, they must be accounted for.

Interestingly, the potential remote range of defenses might, in some cases, mean that there are relatively fewer defenses/defenders at the actual landing site as compared to the WWII scenarios of highly concentrated, localized defenses and defenders.  If this is the case, the need for local bombardment may be reduced. 

The effect of range, then, results in a modification of the definition of bombardment to include not just naval guns but also missiles and aircraft/bombs.

Interdiction – The ability to defend from hundreds or thousands of miles away means that the concept of interdiction has to be greatly expanded.  Interdiction may have to occur hundreds or thousands of miles away.  This also leads to the possibility that there may be no interdiction in the strictest sense of the word since the enemy may have no need to physically move reinforcements to the landing site.  Still, there will almost certainly be some movement of enemy defenses toward the assault site and that movement, however far away, must be interdicted.

Precision Guidance – Many observers mistakenly believe that massive bombardments are no longer necessary thanks to precision guidance.  However, the reality is that precision guidance is a very limited capability in a peer defended assault scenario. 

For example, laser guided rounds are useless in bombardment because there will be no assets available to laser designate.  In a peer defended assault scenario, aircraft laser designators will be unable to loiter over the battlefield providing target designation and ground forces won’t even be available until well after the initial landing and will be too busy surviving to calmly and casually laser spot targets.  Further, the ground forces will be too localized and ‘compacted’ to designate targets more than a hundred feet in front of them even if they were willing to lift their heads above cover long enough to do so. 

Ships can, if so equipped, provide their own laser designation but that would be valid only for visible, line of sight targets and a smart enemy is not going to provide many of those.

GPS guided rounds would be effective but only against known, fixed, visible targets.  The reality is that a smart enemy will not provide many fixed, visible targets.

The reality is that unguided area bombardment is the only generally effective method.

Conclusions  

• For a properly resourced amphibious assault, prolonged and heavy pre-assault bombardment is clearly the preferred action and is essential to ensure a successful landing.
• Post-assault gun support is always required.
• In order for bombardment to be effective and worth the effort, naval gunfire must employ large caliber, heavy guns of 8” or greater size.  As demonstrated by WWII experience, 5” guns simply don’t have the power to effectively destroy hardened fortifications. 
• The area of bombardment on today’s battlefield will likely have to be greatly expanded although the bombardment may take the form of aircraft or missiles in order to achieve the required range.
• Precision guidance is only marginally useful in an amphibious assault.  Old fashioned area bombardment is still required.

Today’s US Navy utterly lacks the capability to provide amphibious pre-assault bombardment or supporting fires during the landing.  If we continue to insist that we want and have this capability, we need to procure bombardment capability.  The Marines long ago gave up their battleship gun support in exchange for a handful of magic beans and promises by the Navy that never came to fruition and they are now left with no naval gun support, whatsoever. 

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(1)“Gators of Neptune”, Christopher Yung, Naval Institute Press, Annapolis, Maryland, 2006, ISBN 1-59114-997-5

(2)Ibid. p.80-81,

From the Overlord Outline Plan: “As preliminary bombardment compromises surprise, it should be confined to the shortest possible duration consistent with the achievement of the required degree of neutralization.”

Mk 45 5" Gun

Let’s get technical, just for a change of pace.  Let’s take a bit of a look at the standard 5” gun of the U.S. Navy.  There have been 5” guns since before WWII but we’ll limit our examination to the modern versions, the Mk 42/45.

This is a bit of a follow on to a previous post on the 5" gun - see, "Mk45 Assessment" - and offers a slightly different perspective and a few issues for consideration.

The Mk 45 was first introduced in the California (CGN-36) class in the early 1970’s and has been the US Navy’s standard 5” gun since.  Interestingly, the Navy’s last two surface warships, the LCS and the Zumwalt, have abandoned the 5” gun.

Historically, the 5” gun has proven to provide a good balance of firepower and size/weight, enabling it to be installed on a wide range of ships.  The gun has proven quite effective in supporting amphibious landings such as Normandy and the Pacific island assaults.  Stories of WWII destroyers sailing right up to the beach and providing pinpoint fire support for assault infantry are common.  

More recently, HMS Liverpool used its 4.5” gun against various Libyan ground targets in 2011, including against shore batteries firing on the British ship.  While the British 4.5” gun is not the 5” gun that is the subject of this post, it does illustrate the continued need for a naval gun of around that size.

Interestingly, all major navies seem to have settled on the 5” gun or a gun very close to that as their standard ‘heavy’ surface ship naval gun.

Here are some relevant characteristics for the Mk45 as reported by NavWeaps website (1).

• Rate of Fire = 10-20 rpm depending on model and type of munition
• Effective Range = 15,000 m (~9 miles) – 24,000 m (~15 miles)
• Mount Weight = ~50,000 lbs depending on configuration
• Train Rate = 30 deg per second
• Fire Control = Mark 86 Gun Fire Control System or the Mark 160 Gun Computing System

Mk 45 Versions:

Mod 0 – single munition type; mechanical fuze setter

Mod 1 – selectable munition from up to six types; electronic fuze setter

Mod 2 – export version of Mod 1

Mod 3 – never produced

Mod 4 – increase to 62 caliber; strengthened supports; longer recoil stroke; stealth mount cover

Note that the mount cover is just a weather covering and provides no protection from shrapnel.  Thus, the mount is susceptible to destruction/disabling from simple shrapnel or flying debris.  Contrast this to WWII 5” mounts which had 1”-2” of armor for protection against all but a direct hit.

The Mk 45 operating crew consists of a gun captain, a panel operator and four ammunition loaders with none located in the gun mount itself.

The 5” gun was considered an anti-air mainstay weapon in WWII but modern 5” guns, while claimed by manufacturers to be anti-air capable, are not generally considered effective in the role.

Let’s consider the history of the modern 5” Mk45.  Unfortunately, there is little combat use to evaluate but here are a couple of notable instances.

Praying Mantis – In April of 1988, the Navy used 5” guns to attack Iranian oil platforms (GOSP) with mixed success – the degree of success depending on who described the action and what they felt the objectives were.

USS Merrill (DD-976, 2x 5”/54 Mk45) and USS Lynde McCormick (DDG-8, 2x 5”/54 Mk42) used air burst gunfire to suppress the Sassan oil platform personnel who refused to evacuate when warned.  Merrill destroyed a 23 mm gun that fired back.  As described by Captain Perkins, commander of SAG Bravo during Praying Mantis,

“At the first muzzle flash from the Merrill's 5-inch mount 51, the Iranian 23-mm. gun mount opened up, getting the attention of the ship's bridge and topside watchstanders. The Merrill immediately silenced the Iranian gun with a direct hit, and encountered no further opposition. After about 50 rounds had exploded over the southern half of the GOSP, a large crowd of converted martyrs gathered at the northern end. At this point, we checked fire and permitted a tug to return and pick up what appeared to be the rest of the Sassan GOSP occupants. Following this exodus, the Merrill and the Lynde McCormick alternated firing airbursts over the entire GOSP …” (2)

At the Sirri GOSP, the USS Wainwright (CG-28, 1x 5”/54 Mk42), USS Bagley (FF-1069, 1x 5”/54 Mk42), and USS Simpson (FFG-56, 1x 76 mm) exploded a compressed gas tank and set the platform ablaze.

Capt. Perkins reports that 208 rounds, total, were fired at Sassan and Sirri oil platforms.  Perkins noted that the structure of the platforms, with thin supporting legs, precluded effective naval gunfire and necessitated suppression followed by insertion of troops to destroy the platforms via demolitions.

Vincennes Incident – During the incident, the Vincennes attacked a group of possible Boghammer type speedboats but failed to record a hit despite around a hundred rounds being fired.  Initial reports indicated that two boats were sunk and a third damaged but later reports could not confirm any hits.  During the attacks, one of the 5” guns failed and the Vincennes had to maneuver to unmask the remaining gun.

Consideration of the 5” gun leads to several questions/issues:

Multiple Mounts – More guns are always better.  Guns always jam and fail – the Vincennes failure of one gun being a modern example.  If it’s worth having one gun on a ship, it’s probably worth having two or more for redundancy and reliability.  In combat, guns get damaged or destroyed and redundancy is critical.

It’s interesting to note that the Tarawa class amphibious assault ship was originally built with 3x 5” guns!

Dual Mounts – Given the scarcity of 5” mounts (one per Burke), one can’t help but wonder why dual gun mounts aren’t used to increase the ‘throw weight’.  An example of a modern dual 5” mount is the excellent Soviet AK-130 which houses two 130 mm (5.1”/70 cal) guns with a range of 23,000 m (~13 miles), a 500 round magazine (Sovremenny) and 150+ ready rounds.  In fact, the Sovremenny class carries two AK-130 mounts for a total of 4x 5” guns as compared to the Burke’s single gun.

Range – The 5” gun is the Navy’s only naval gunfire support weapon and its limited range requires close approach to shore in order to provide fire support which is at odds with the Navy’s stand-off doctrine and necessitates risking a multi-billion dollar Aegis ship.

Various extended range programs have been attempted in the past and have failed but one can’t help but wonder if a basic extended range munition/gun can’t be developed.  Previous efforts (ERGM, BTERM, and the like) have attempted to be near-magical and incorporate multi-mode guidance, advanced warhead performance, complex flight control systems, etc.  It would seem that a simple, extended range, unguided shell would be highly useful to support ground operations.  In other words, no electronics, no guidance, no advanced warhead, no flight control, no networking, none of the things that drive up costs and cause such programs to fail – just a dumb shell that travels further.

Armor – Current gun mounts are completely unprotected other than a weather cover.  As noted, WWII 5” mounts were protected by up to 2+” of armor.  Again, if a gun is worth having, it’s worth protecting it against near misses, shrapnel, and other easy kills.  This is all about keeping a ship combat-capable as long as possible in a fight.

Gunship – It might be worth considering developing a modern equivalent of the WWII Fletcher which mounted 5x 5” guns on a small hull.  With the addition of a navalized M-270 MLRS rocket launcher, one would have a compact, moderately powerful fire support vessel.

In summary, there is every reason to believe that a general purpose 5” gun is still a valuable addition to a modern warship although it should be installed in multiple, dual gun mounts to enhance its firepower and ensure its combat viability.  In addition, an extended range, unguided shell should be developed to extend the usefulness of the gun.

Note, that this is not to say that the 5" gun is the ideal naval gun.  ComNavOps is on record as preferring the 8" gun as indicated in the previous post.

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(1)NavWeaps website, weapons/guns/United States of America/5"/54 (12.7 cm) Mark 45 Mods 0 – 2, retrieved 23-Sep-2017,

http://www.navweaps.com/Weapons/WNUS_5-54_mk45.php

(2)USNI Proceedings, “Operation Praying Mantis: The Surface View”, Captain J.B. Perkins III, USN, May 1989,

https://www.usni.org/magazines/proceedings/1989-05/operation-praying-mantis-surface-view