Steve McLaughlin posted the following description of the origins of the battlecruiser (19/06-98)

Sometimes considered an amalgam of the battleship and the cruiser, this fascinating and usually beautiful vessel has generated a great deal of controversy through the years over its real value in battle.

In the 1890s a new breed of armoured cruisers began to emerge, one that had more extensive armour. This was possible thanks to improvements in the technology of armor manufacture, which allowed thinner plates of face-hardened Harvey and then “Krupp” armor to offer the same resistance as much thicker steel or compound (steel face/iron backing) armor plate. So the weight saved on thickness was used to increase the area protected. Improvements in boiler and engine technology also allowed the new generation of armoured cruisers to have a substantially higher speed (say, 21 knots vs. 18 knots) than contemporary battleships. This had not been the case previously -- the big cruisers of the 1870s and 1880s had very little speed advantage over battleships, or bought what advantage they had at an enormous price in weight devoted to machinery.

Add to this brew another factor -- the rise of the rapid-firing (or quick-firing) gun of up to 6-inch caliber. The rapid rate of fire of these guns, and the still slow rate of effective fire of the 12- inch pieces, made it seem possible for a fast ship armed with rapid-firing guns to take on a slower, heavily-armed ship with only a few big guns and a battery of quick-firers no more powerful than the cruiser's -- especially since many gunnery authorities held that big guns could not hit at long range, since there was no effective way to control them. The time-lag between salvos meant that spotting would be virtually useless (the target ship would move so much between salvos that the fall of shot from the last salvo would be relatively useless for estimating his future position for the next salvo). Rapid-firing guns, on the other hand, could "hose down" a target by "walking" a series of rapid shots across it, thereby finding the range quickly. Thus armored cruisers might actually have an advantage over battleships at some ranges, and some proposals (in Italy and Russia) were put forward for ships armed exclusively with 8-inch guns (which were seen as the ideal combination of rapid-fire with armor-piercing). In general, however, armored cruisers were fitted with a few big turret guns fore and aft (8-inch to 10-inch) to act as "closers" that could penetrate the other fellow's armor once his topsides had been chewed up by the quick-firers at longer ranges.

There was a time when these new armored cruisers seemed the coming thing, and one French admiral, Fournier, argued in the mid-1890s that they were in fact "universal" ships that could fulfill the role of battleships and of commerce protecting (or commerce raiding) ships.
At the Battle of Tsushima in May 1905 Admiral Togo used his armored cruisers as part of the battle line, and did so quite successfully. Admiral Kamimura's cruisers were essentially a "fast wing" of the fleet that operated semi-independently of Togo's battleships.

Now we come to Jacki Fisher. Perhaps having read some of Admiral Fournier's writings (he was reportedly well-regarded in Britain), he conceives the idea of a new "universal" ship, a super-armored cruiser capable of both protecting trade and standing in the line of battle thanks to its superior speed. Fisher's famous dictum, "Speed is armour" may well derive from his belief that advanced types of fire control gear then under development (by A.H. Pollen) would make it possible for the fast super-armored cruiser to stand off and destroy a slower, more heavily-protected enemy battleship at ranges where the battleship could not fire effectively. Hence armor on the super-armored cruiser would be minimal, so that more weight could be devoted to guns and machinery. An indication of Fisher's program may be seen in the fact that he managed to get three of these super-armored cruisers laid down after the first, eponymous DREADNOUGHT battleship was started. To him, the DREADNOUGHT was just a better battleship, but the super-armored cruiser was a "universal" ship, a "New Testament" ship that would completely alter the way war was fought at sea.

The fly in the ointment, of course, was that (largely through the Admiralty's own blindness), the fire control gear on which the whole concept was based was never fully accepted by the service. (Even had the Pollen gear been adopted and proven as successful as advertised, one wonders what would have happened to such lightly- protected ships once the enemy developed his own long-range gunnery control, nullifying the advantage of the British ships -- but Fisher doesn't seem to have taken this inevitable possibility into account.) This condemned the British battlecruisers (as they were eventually designated) to being little more than a super-scouting force when acting with the battle fleet, and as far as I can tell there was no particularly well-thought-out tactical doctrine for their co-operation with the slower dreadnought battleships of the Grand Fleet. But the idea eventually became accepted that they would add their immensely valuable 12-inch and 13.5-inch broadsides to the general engagement -- what admiral could do otherwise, with such fine ships in his force?
A reasonable man such as myself could be led to argue that the term "battlecruiser" -- which was only introduced shortly before the Great War -- was a complete misnomer, as these ships were unfit to lie in the line of battle once the superior fire control rationale fell through. But then, the name stuck, so we have to deal with it.

Other navies designed battlecruisers that were perhaps more worthy of the name. Lacking Fisher's original conception (with advanced fire-control at its heart) to guide them, these navies returned to the 1890s conception of the armored cruiser, but magnified to dreadnought proportions. Thus, in Imperial Russia, the battlecruiser was from the start conceived of as a ship fit to lie in the line of battle; taking a page from Togo's book, the Russians designed their IZMAIL (or BORODINO) class battlecruisers as a "fast wing" of the battle fleet. This fast wing would be used to overhaul the head of the enemy's line and concentrate its fire on the flagship, thereby beheading the enemy's fleet and throwing it into confusion (again, just as Togo had done to the Russians at Tsushima). The armor of the IZMAIL class was actually heavier than that of the first Russian dreadnoughts, which were, admittedly, armored on a rather light scale. To emphasize their tactical role, the Russian designation of these ships was "Cruisers of the (battle) Line."

I would imagine that Germany was guided by similar thinking, although I have nothing specific to indicate that this was the case -- beyond the design of the German battlecruisers, which were armored on a sufficient scale to survive in the battle line. The Japanese also seemed to lean toward the concept of an armored cruiser that could stand up to a general engagement; the early semidreadnought armored cruisers of the TSUKUBA and IBUKI classes were a direct result of Tsushima, and even the British-designed KONGO class an 8-inch belt, two inches thicker than any of the early British battlecruisers. Only the United States, which got into the battlecruiser business late (there was a general prejudice against high speed in the USN), went whole-hog for the "Fisher-ite" conception of the battlecruiser, designing the enormous, thin- skinned LEXINGTON class. These were much modified in the light of British experience, as transmitted to the USN by visiting constructor Stanley (later Sir Stanley) Goodall, and a lot of armor was added.
The "pure" (Fisher-ite) battlecruiser as a viable tactical conception was discredited at Jutland, and now the terminology gets rather strained. After the First World War, Britain finished HMS HOOD to a much modified design, with much heavier armor -- she was more of a fast battleship than a battlecruiser, but the original name stuck. Likewise, magnificent, never-built G3 class "battlecruisers" were more heavily protected than any existing battleship -- their only claim to battlecruiser status came from their high speed. The parallel N3 class battleships were slower, and armed with 18-inch guns; they were given a much lower priority than the "[/I]battlecruisers[/I]." The Japanese were likewise designing a parallel series of battleships and battlecruisers, where the only difference between types was slightly thicker armor in the battleships, and slightly higher speed in the battlecruisers. The Italians were building the "fast" battleships of the FRANCESCO CARRACIOLO class (25-knot ships); only the USN still adhered to the slow battleship idea, still working on the somewhat dated (but very powerful) SOUTH DAKOTA class. The improved LEXINGTON class ships would have been roughly equivalent to (and somewhat more powerful than) the HOOD.

To be continued…

The general trend was toward faster battleships and more heavily protected battlecruisers, and many authorities argued that the two types would eventually merge in a true fast battleship. The problem was, such a ship would be very large and expensive, and no one wanted to take the plunge all at once and start building this new type. In a way, however, it can be seen as an echo of Fournier's 1890s conception of the "universal" ship.
The Washington Treaty canceled all these ships; using existing ships as a guide, the Treaty's writers decided that future battleships should be no more than 35,000 tons and carry no guns heavier than 16-inchers. This combination almost inevitably killed the fast battleship concept -- there simply weren't enough tons to build a powerfully-armed, well-protected, high-speed ship. Since future construction was limited in numbers, and no one wanted to build less powerful ships than the other guy, most navies returned to basically slow (21-23 knot) ships. Britain built NELSON and RODNEY, which were scaled-down versions of the G3 battlecruiser design. Wishing to retain the nine 16-inch guns of the G3 (to match the eight 16-inch guns of the US and Japanese ships), as well as the main elements of its armor protection, the British were forced to cut the speed to 23 knots (although the USN considered even this a "high" speed for a battleship).
NELSON and RODNEY formed the basis of much inter-war designing -- the rebuilt US super- dreadnoughts IDAHO, MISSISSIPPI and NEW MEXICO were given "NELSON- like" tower masts, the French DUNKERQUE and STRASBOURG were based on NELSON, and the Soviets and Japanese also tinkered with some all-guns-forward designs.

The French DUNKERQUE and STRASBOURG were the only "special purpose" capital ships built under the treaty system. France had been allowed new construction under the original Washington Treaty since she had been unable to complete any modern battleships during the First World War; she did not take advantage of this permission until the appearance of the German "pocket battleships," which could easily outrun her old dreadnoughts and could threaten her trade and connections to North Africa in the event of war without Britain as an ally. These two beautiful ships started a whole new round in the battleship/battlecruiser debate. Basically armored on a battleship scale, but with a relatively light main battery and high speed, some writers started calling them "battlecruisers" -- which could only be taken to mean that a ship with good armor but light guns had usurped the name. Seen in the context of the original German and Russian (and probably the Japanese) conception of the battlecruiser, this was not necessarily wrong; it was only when seen in terms of the "Fisher-ite" lightly-armored battlecruiser that it can considered a misnomer.
DUNKERQUE and STRASBOURG were followed by a whole generation of "light battleships" or "battlecruisers," some slanted toward protection, others toward guns. I am aware of the following designs:

SCHARNHORST and GNEISENAU: Politically motivated ships, intended to counter the French ships; they were forced to use a light armament of 11-inch guns because these were already in the works for the next pocket battleships, which they replaced. The Germans believed that the higher rate of fire of the 11-inch guns would allow these ships to face the French ships armed with 13-inch guns; but they had to have deficient protection to withstand the bigger French gun, hence their heavy protection. They do not seem to have been specifically intended to act as commerce-raiders, and had steam propulsion rather than the long-range Diesels of the pocket battleships.
The rebuilt Italian dreadnoughts JULIO CESARE, CAIO DUILIO, CONTE DE CAVOUR and ANDREA DORIA were intended to face the French DUNKERQUEs. In a sense, then, they fit into this new category of "light battleship/battlecruiser." The Italians also toyed with the idea of building new 12-inch gunned battlecruisers, but dropped it.
The Soviets decided that they required two types of capital ships, a big ocean-going ship (which became SOVETSKII SOIUZ) and a smaller ship for the Baltic and Black Seas, which started out as a small battleship, then became the "heavy cruisers" of the

KRONSHTADT class. These ships were meant to face the German SCHARNHORST class, and so were given bigger (12-inch) guns and higher speed, but weaker armor (perhaps the Soviets did not appreciate how far over their announced displacements the German ships were, and so assumed they had less extensive or thinner armor than was the case). These ships, called "battlecruisers" in the west, were more in the nature of "cruiser killers," and, as their Russian designation implies, were never meant to slug it out with real battleships. They were never referred to as "Cruisers of the Line" by the Soviets, and the term "heavy cruiser" was apt (although somewhat confusing in light of its use in the west for 8-inch gunned cruisers -- of which the Soviets had none -- hence for them there was no terminological conflict).

The Dutch projected several "cruiser killers" for their East Indian possessions. These ships were in essence also "Fisher-ite" battlecruisers, with high speed, light armor and a battery of 11- inch guns. They were intended to fight the numerous Japanese heavy cruisers, since the Dutch calculated that the main Japanese forces would be tied down by the RN and/or USN, so they would have to counter only detached forces.

The US designed the ALASKA class as super-cruisers. The USN had wanted these ships for a while; the growing gap between battleships (35,000 tons escalating to 45,000 tons when the Japanese refused to accede to the 1936 London Treaty) and 10,000-ton treaty "treaty" cruisers seemed to cry out for a new, larger cruiser. There were also rumors of Japanese "pocket battleships" to be countered. Like the Soviet and Dutch ships, the US ships were essentially "cruiser killers" unfit for the line of battle, and the term "battlecruiser" can therefore be seen as a misnomer; like the Soviet "heavy cruiser" designation, the US "large cruiser" classification of these ships is a fair one.
The rebuilt KONGO class battlecruisers are generally classed as "fast battleships," and on the whole I think this is apt; tactically, I do not think the Japanese planned to use them as "classical" battlecruisers; at most, they would be used for carrier escorts (I believe this was the main rationale for their high speed), and perhaps to support independent cruiser groups. But I believe (I may well be wrong) that they were still perceived as having an important role in a battle fleet action.
The Japanese toyed with the B-64/65 design after hearing rumors about the US "large cruisers" (ironically, the Japanese had virtually no interest in "pocket battleships," as commerce-raiding formed a very, very minor part of Japanese doctrine, which concentrated on the big clash of battle fleets). Thus the US response to a mythical Japanese pocket battleship triggered a real Japanese pocket battleship. It seems that the Japanese had no specific tactical concept for these ships, and I gather they would have been used as part of the "attrition operation" of night attacks and air and submarine attacks designed to whittle away at US battleship supremacy before the big battle.
The Germans, as part of the "Z Plan," designed a class of very fast, very lightly-protected, very long-ranged ships with battleship-sized batteries -- the "O" class. These ships seem to have been "Fisher-ite" in conception -- that is, they were to be used in commerce raiding (hence the long cruising range) or perhaps as scouts for the new generation of battleships. But they were by nature unfit to lie in the line of battle.
As far as I know, the British never seriously considered this type of ship, although I believe the VANGUARD design was originally thought of as a battlecruiser. However, the rebuilt RENOWN and (to a lesser degree) REPULSE, as well as the proposed rebuilding of HOOD, do give Britain a place in this category. I am not aware of any British doctrine that gave these older battlecruisers a separate tactical or strategic rationale from the battle fleet proper, although the dispatch of the battlecruisers to hunt the pocket battleships indicates that they were perhaps seen as more cruiser-killers than "light battleships." Yet RENOWN certainly chased off SCHARNHORST and GNEISENAU off Norway, and HOOD was certainly used as a battleship.

Finally, the Soviets after the war designed the STALINGRAD class "heavy cruisers" -- extremely high speed ships with 12-inch guns and light armor, whose main role was apparently raids on the enemy's maritime communications -- i.e., commerce warfare. Once again, the Soviet designation seems appropriate, since these ships were never meant for "battle" with enemy capital ships.

So, assuming anyone has bothered to read this far, where does this leave us? I would argue that the term "battlecruiser" as sometimes used in the WWII era -- that is, for a well-protected fast ship with relatively light guns -- makes sense in the Russo-German conception, but not in the British/American sense of a high-speed ship with light armor and big guns. In other words, we have two separate traditions to take into account, and a single term has been used to cover two very different kinds of ship. I am not going to propose a new terminology, but I will suggest the following classification scheme:

Fast Light Battleships:
--DUNKERQUE and STRASBOURG
--SCHARNHORST and GNEISENAU
--The rebuilt Italian dreadnoughts, just barely
--The rebuilt Japanese KONGO class
--HOOD (not so light, of course)
Super-Cruisers:
--KRONSTADT class (although their anti-SCHARNHORST role gives them a nominal "battle fleet" role)
--ALASKA class
--Dutch East Indies "Battlecruisers"
--German "O" "battlecruisers"
--STALINGRAD class
--RENOWN and REPULSE (but with a little battle fleet work thrown in)

Cimbri

What are your thoughts?

Had Invincible and her sisters been built with 9.2" guns, and not put in front of guns they weren't intended to face, they'd have just been an evolutionary step, and probably a successful one too.

The German battlecruisers and the English Queen Elizabeths count as spectacular successes, and either one is a fine starting point for developing hypothetical better 1920s warships... just didn't turn out that way in practice immediately, though eventually the fast battleship did emerge.

But if you mean, was the concept behind Invicible->Lion->Repulse->Furious sound, no, except for a few very specific uses, and very few navies can afford to build such special-purpose ships (or manage to get them in the right place at the right name, and keep them safe the rest of the time.) It's a basic fact of war that the enemy WILL shoot back.

Re your basic classification, I agree in general, though we can argue about details. The super-cruiser and the fast-battleship are two quite different animals.

While one may argue that Jutland discredited the Fisherite BC, Coronel/Falklands is a pretty strong argument for their utility in any situation other than the line of battle.

And one can certainly argue that without Beatty's mishandling of the BCF and a significant design deficiency which was common to ALL British BBs and BCs on 31 May 1916, and was generally found in all navies (protection against cordite flash), the BCs could have executed their intended role at Jutland.

Had the BCs not been vulnerable to the cordite explosions, and had Beatty withdrawn at the correct moment and handled the 5th BS appropriately then the BCs would have covered the Grand Fleet in precisely the doctrinal fashion.

Their speed advantage over the High Seas Fleet enabled the BCF to break contact effectively, and the BCF then crossed the GF's line of advance, covering the deployment into line.

I would suggest that the distinct BC vs BB specialisation (the 'Fisherite' BC) was driven by the propulsion technology of the early 20th century. The very great demands of coal fired propulsion for bunkering forced a choice between armouring and speed. Once oil firing was adopted it was possible to design a compromise ship which was capable of useful speed AND line-of-battle armour. The fact that the Queen Elizabeth's were considered BBs, but fought Jutland with the BCF, shows how quickly this happened.

Some of the 'tween Wars developments were skewed by economic or treaty constraints; once those were lifted the trend was for "fast" BBs of varying degrees, and the extreme BC was no longer really needed.