A battleship as built can be seen as the sum of the answers to a whole series of questions, ranging from the highest levels of national strategy down to the most mundane issues of how best to operate a large and complex pile of machinery. A full and comprehensive analysis of all of these questions and their answers for even a single ship would require a whole book (actually several bookcases in danger of structural collapse), but I'll attempt a high-level overview here.
The Austro-Hungarian fleet on maneuvers
The first major question that shapes a ship is "What do we want our fleet to do?" The answer is informed by the strategic situation and the resources available, because there's never enough money as we'd like. We've previously looked at the basics of naval strategy, and the broad choices available to a navy. But how do battleships fit into this framework?
Battleships were essentially symbolic of sea control from the 1860s up until about 1940, when the torch was passed to the aircraft carrier. Control of the sea involves being prepared for the worst possible fight the enemy can throw at you, while sea denial forces can afford to pick their battles, striking where the enemy is weak and circumstances favor them. This isn't to say that sea control forces can never refuse to fight when the odds are too badly against them, but avoiding a fight surrenders a portion of that control. Avoid too many, and you're no longer master of the seas. While there were weapons in the late 1800s that could defeat a battleship some of the time and under certain circumstances, it took until the 1950s to reach the point that the heavy guns of the battleship were no longer an important part of a balanced fleet. The fleet aspect is very important. While I focus most on the battleships, they did not work alone, and their supporting ships dealt with many of the supposedly lethal threats. Nor were battleship tactics static. As new weapons made previous options too dangerous, navies invented new ones.
Torpedo Boat HMS Lightning
The first weapon that was supposed to doom the battleship was the torpedo. Before its invention in 1868, the only weapon that could defeat a ship was a big gun, which required a big ship to carry it.1 Torpedo boats were small and cheap, and each could, in theory, sink a battleship. This was the position of the French Jeune Ecole, who claimed that the traditional close blockade was now impossible. The development of the destroyer reduced the torpedo threat to a manageable level, and the close blockade was replaced by the distant blockade. The distant blockade, such as the British blockades of Germany during the World Wars, was usually enforced by light units, but they had to be covered by a battle fleet to prevent heavier enemy units from snapping them up.
A flotilla of German U-boats during WWI
In the runup to WWI, the submarine had taken the place of the torpedo boat as the potential battleship killer. Even such luminaries as Jackie Fisher believed that the submarine would make it impossible for the battleship to operate in the North Sea. What actually happened was that the slow speed and limited vision of the submarine made it mostly ineffective against warships with appropriate screens. Despite scattered successes, the submarine remained far more useful for hunting merchant ships than warships until the 1950s, when nuclear power finally allowed submarines to achieve their full potential.
The former German battleship Ostfriesland during air attack trials
After the war, air power advocates such as Billy Mitchell claimed that aircraft would sink any ship which approached the coast. At the time, aircraft simply were not up to matching this boast, and without better sensors than the Mk I eyeball, even detecting ships at sea was a serious problem. During WWII, the carrier replaced the battleship as the main instrument of sea control, but even so, this represented a defeat for the sea denial advocates. Battleships gave valuable service screening the carriers from both air and surface threats. Even as late as the early 50s, aircraft carriers remained vulnerable to surface attack at night or in bad weather,2 and it was only the lack of foreign battleships that allowed the sea control powers, Britain and the United States, to place their ships in reserve. Nuclear missiles3 and improved aircraft finally rendered them obsolete except for bombardment work.
The 1911 Coronation Review
After figuring out that battleships were a good choice for their strategy, powers had to figure out how many to buy. The British, whose goal was control of the seas surrounding Europe,4 adopted a two-power standard, declaring in 1889 that they would build a fleet equal to the fleets of the next two strongest powers combined. This persisted until Germany began the dreadnought race, when it became 160% of the next-largest fleet. The US first attempted to build a fleet capable of keeping likely threats (in practice, Germany) from being able to establish a base in the New World, and later a fleet capable of overmatching the Japanese and equal to that of Britain.5
I should emphasize that while some countries bought battleships based on a sound strategic rationale, a lot of them didn't. Ships were bought because they would add to national prestige, or because the Navy was trying to gain political power. But regardless of the reasons for the purchase of battleships, the problem then passed into the hands of the naval architects who had to design the ships.
1 Strictly speaking, ramming was sometimes proposed as dooming the large, gun-armed ship even earlier, but I'm going to stick to weapons that actually worked more than occasionally. ⇑
2 In 1982, the British considered the Argentine light cruiser General Belgrano a serious threat to the fleet sent to retake the Falklands, if she could approach without being attacked by aircraft. ⇑
3 Most SAMs have some anti-ship capability, and their secondary anti-ship/bombardment role was an important consideration in US nuclear-tipped SAMs. ⇑
4 This translated into control of the global seas thanks to naval geography, at least until the early 20th century. ⇑
5 At least in theory. In practice, the main limit on the USN battle fleet throughout much of the era was Congress, who was often suspicious of the rationale for naval power. ⇑
Comments
Thanks!
I don't think I had realized that big guns required big ships; I had gotten the impression that the defining characteristic of a battleship was its armor rather than its guns. It makes a lot more sense as a gun platform that happens to be survivable than as an armored platform that happens to have some weaponry.
There are definite limits on how big of a gun you can put on a small ship. For instance, the German attempts to put 6" guns on destroyers were not very successful. The guns were too heavy and the recoil was too much for the hulls. You could fit a big gun on a small hull, but usually only by compromising other features. Monitors and coastal defense ships are the usual examples, but these have specific tactical niches and couldn't really replace a battleship.
Once you make the ship fast enough to be useful and big enough to have decent seakeeping, you're edging into battleship territory already. You could in theory build one without armor, and John Schilling might say it's a good idea. I'm less certain. Armor certainly isn't perfect, but without it you have the serious risk of ships with small-caliber guns not just mission-killing you, but actually killing you.
Are there any modern cases where more than de-minimus armor has actually helped? From what I can tell, it's either Somali Pirates shooting for which the basic hull would probably be sufficient, or it's an attack like the USS Cole which was effectively a mission-kill. From what I can tell, on a war-time footing, carriers would prevent anything from getting close enough to attack. And on a peace-time footing fatigue and merchant vessels are enough to take out major ships.
Not enough to make armor worth bringing back, no. The big difference is that it's become much easier to build weapons that can comprehensively beat armor. A modern ASM might be stopped by sufficiently thick armor, but it's a lot easier to build a better ASM or ASM warhead than it is to build an armored ship, and it's generally seen as better to try to stop it before it hits anyway.
Mention of monitors makes me think. You covered bombardment as one of the reasons for the Iowa reactivation in an earlier column; a battleship is probably overkill for the role, but a purpose-built, lightly armored heavy gun platform seems like it'd be much cheaper for the niche. Range would remain an issue, but precision guidance for artillery is now available with Copperhead and similar systems, and there's no reason that couldn't scale up past 155mm.
@Nornagest
I'm not bean, but I'll have a crack at that.
I suspect you're right in identifying a niche that exists, but the question is always going to be opportunity costs. An unarmoured shore bombardment platform would be a very specialised tool indeed. Only navies with, at minimum, green-water capability would be interested--otherwise, who is it going to be shooting at? It'd have to come close to shore to fire and it can't hide once it starts firing anyway, since ballistic trajectories give it away, so it couldn't be deployed anywhere where anyone's likely to be shooting back.
The US Navy could build such a thing, and might even get use out of it: something like intervening in a second Sierra Leonean civil war would be a practically tailor-made mission, but it'd be too risky to use in a hot war against China or even Iran unless their shore defences had already been silenced.
But the US Navy isn't lacking for strike options as it is, so why spend the men and steel on such a limited-use ship instead of putting that towards another destroyer that can also strike targets ashore, either from further away with its missiles or cheaply from close with its gun, and can do other useful things on top? The unarmoured big gun platform would have to be much, much cheaper than a guided missile destroyer to make that worthwhile, and I'm not sure you can make a big ship cheap enough for that to be a good trade.
@Nornagest
A monitor is definitely a possible solution to the lack of USN bombardment capability, and it is sort of ironic that the Iowas, famed for their speed, spent most of their lives in that role. You could make it a lot cheaper to operate than a battleship, and fit it with a modern gun with guided rounds and a good support system. 20 kts, shallow draft, RAM and CIWS, and it shouldn't be terribly expensive to build either. The problem is development cost, because every attempt for the last 40 years to develop a gun heavier than 5" has failed. Personally, I'm of the opinion that we'd do better building a bombardment weapon that fits in existing VLS cells, which is why I didn't talk about it as an option earlier.
@sam
Pretty much in line with my thoughts. Coming in close is dangerous these days, and you get fairly minimal capability in a hot war. In terms of cost, steel is cheap, but design work isn't. If we could figure out a way to shoehorn it onto a hull we already have in production (cut AEGIS off a Burke or something) it might make sense.
There's a part of me which thinks a big gun could be a valuable addition to my hypothetical Presence/Strike Cruiser, simply because guns are very easy to understand, and thus excellent at impressing the locals with how powerful the USN is. But I'd also want to keep development costs down, and not get in the way of the ship's primary mission of serving as a command ship. Not sure if that's possible, and if it isn't, then don't bother.
@sam, @bean
What about having gun modules which could be attached to existing cargo ships? It allows them to be in storage until you need a large volume of fire, and then you can rent/nationalize a few cargo ships and vastly increase your firepower.
Alternatively, would we be better off just stockpiling munitions and having a cargo ship do extra supply runs?
No.
The long answer is that there's lots of subtle problems with this. Big guns need strong (as in purpose-built) foundations. During the World Wars, this meant that the limit on merchant raider weapons was 6", because that was the biggest you could fit without it being a dedicated warship. For a modern 5" gun, you're not really going to just bolt it onto a cargo ship, because the magazine takes up a bunch of volume belowdecks. The Danes have 3" in StanFlex, and that strikes me as about the biggest that could be used this way, but it's too small for good monitor work. Of course, this assumes you have the right kind of power supply, and enough chilled water. And then you need to make sure that commands get to the ship, so a bunch of radios. And it would be irritating to lose the ship to a single missile boat, so you need point defenses and at least some EW suite. And maybe we want some situational awareness. So now we need more people, and merchant ships don't have enough accommodations. And even after that, the ship has no damage control facilities, and sitting close offshore is a dangerous place to be. Neither the crew nor the owners like this plan. And it's slow, and it uses spares not in your logistics systems and...
That's a better plan, yeah. The big issue is that cargo ships aren't set up for underway replenishment, so you're actually likely to be going cargo ship>ammo ship>bombardment ship.
I'd say that it's a good idea to build your capital ships with no more armor than it takes to stop 8" AP at close range, and maybe a good idea to just provide as much coverage as you can against 6" HE. But you don't want to leave yourself open to cheap kills by allowing any cruiser that gets within reach to put HE shells into your engines and magazines.
Actually, you probably also want to armor against 16" HE just to force enemy battleships to carry the specialized and less destructive AP shells. That overlaps the sort of armor you'd need against 8" AP.