Ship roles

I have a question which may make me sound stupid, but if I get an answer and lean what I want to then it is a price I am familiar with and willing to pay!!

I have become confused about what role certain classes of ship played in a navy or even a fleet. I understand that carriers are to project air power to places unreachable by land based aircraft and that in the early stages battleships were intended to be a dominant force in a naval theatre of operations. Destroyers were used as convoy escorts and submarine hunters.

What I am at a loss to understand (through a lack of any good material) is what role a cruiser filled (other than designated AA cruisers)? I also dont understand why destroyers were the main convoy escorts when speed was generally no more than 25 knots even for a fast convoy (except for russian convoys). Surely more powerful ships with more AA would have served the purpose better, which would explain a role a cruiser could fill?

When it comes to the pacific war (an area I have very little knowledge of) I dont understand the fleet composition. Surely a smaller more nimble ship like a frigate would have served as a smaller target for aircraft and a better sub hunter than a destroyer? Other than AA fire, I dont understand the need for cruisers or battleships in a carrier fleet.

If someone could provide me with links, books, documentaries or just answers for these questions I would be grateful.

 

First we have to note that these traditional roles were all in flux. I don't think we can identify any time after the advent of steam, armor, torpedoes, etc. when such things reached status.
The aircraft carrier began as a scouting asset, then took on more actively offensive roles such as spotting gunfire for other ships and even launching attacks directly at enemy ships. Hindsight has tended to muddle this issue, and "muddle" may be too tame a word. But by 1945, the long range of carrier planes and their versatility in engaging ships, submarines, aircraft, and land targets had made them the most bang-for-the-buck weapon system for any navy with a wide-ranging mission.
The battleship is the traditional command-of-the-sea determiner. The battleship could sit on a sector and nothing could push it off except another battleship. Having accomplished this, the battleship then made it possible for other vessels (transports, freighters, and so forth) to travel the sector in safety. In modern terms, this is sea lines of communication. An aircraft carrier escorted by a battleship can go anywhere it wants; a carrier with no battlesihp must take care not to get too close to an enemy fleet.
The cruiser tradition got mangled perhaps more than any other. It was the primary scout for the battle line. It was the primary agent of commerce protection, and of commerce raiding. In general, it had to fend for itself on difficult independent tasks of various types. It also played an important role in screening the battleships or even getting into a battleship "scrum" if necessary. With all these roles, the cruiser split into various types--smaller ships that could be built in large numbers for their many jobs, and giants as large as (or larger than) battleships. The modern battleships of WWII are descended not only from older battleships but also from these giant cruisers, which eventually had won the label of "battlecruisers." At the same time, the smaller cruisers often served humbly as destroyer leaders. Ultimately, it may be best to think of the WWII cruiser as the protector of larger warships that could also go its own way if needed; but with ships ranging in size from 3000 tons to nearly 30,000 tons all wearing the cruiser label, you understand there's no single definition that will work for them all.
The destroyer was originally a "torpedo boat destroyer" in function and an overgrown torpedo boat in nature. Keep in mind that torpedo boats in this context were steam-driven warships, not the PT-boats or MTBs that we associate with WWII. In fact, the destroyer took over the role of the torpedo boat. It carried torpedoes on a high-speed platform that could charge and threaten enemy capital ships; at the same time, it could protect friendly capital ships from the enemy's torpedo attacks, though you really would want a cruiser to do the job right. Destroyers also earned the task of an anti-submarine unit. Cruisers often carried ASW weaponry, but the destroyer was much better suited (and present in larger numbers) for it.
"Frigate" was a term resurrected from the age of sail and imposed on a new kind of ship simply because they needed a name for it. (The same thing happened to "corvette.") It was applied mostly to a ship the size of a small destroyer but constructed to mercantile standards. It couldn't match the destroyer in weaponry, but it had defensive systems specialized to match its role as a convoy escort. It is not a fleet unit, and would rarely rub shoulders with battleships or carriers.
That's a big rambling answer, and surely I've missed some things. But there will always be more to be said.

 

Although they are expensive and take a long time to read, the best series of books detailing how the roles of various warships evolved over the last 100 years is probably Norman Freidman's Illustrated Design History of United States Warships.

There is a volume for each type of ship, Aircraft Carriers, Battleships, Cruisers, Destroyers, Submarines (two volumes for submarines), and Small Combatants. Friedman provides the history of how and why these ships developed the way they did and the sea warfare that caused them evolve over the years. Included are numerous photos, line drawings and schematics of warship designs and tables oof specifications, plus lists of US warships laid down.

 

Battle cruisers= armed around the same as a Battleship, but not as heavy amoured usually used for commerce raiding due to there speed.

Battleship = Once the King of the seas she was capable of taking on any other surface ship and that was her prime objective.

Crusiers = Are generally nothing more then heavier armed and armoured destroyers, generally used to screen larger ships like Carriers and Battleships, allowing them to do all the damage on the enemy ships.

Destroyers = Used for convoy escorts due to there speed and the fact that they had the capabilities to chase down submarines with ease, this advantage also made them harder to hit by the submarines when not in convoy formations.

Carriers= well that depends on the area of operations, for example, the Pacific they were used as forward air bases, to bomb enemy carrier groups, airfields, and protect other allied vessels.

While in the Atlantic they were mainly used to hunt commerce raiders and bomb submarines and such.

 

This is great guys. Being a new mwmber its really good to find this site and to get such a good start on this thread. Finding knowledgable answers to questions is not always easy, but this site loooks l ike it will help!!!

 

Historicly the cruiser (a term coined in the 17th century) was more of a role (scouting, carrying dispatches, disrupting enemy trade etc.) than a type of warship. By the late 19th Century "cruiser" fit any ship larger than a destroyer, and smaller that a battleship. It wasn't untill the Washington Naval treaty that a displacment was set to them (under 10,000 tons)and the London Naval treaty before a split between heavy and light cruisers was distinguished.

 

And this obscures the fact that battlecruisers were cruisers.

 

While this is true, I was only trying to point out that it wasn't untill 1922 that a definitive "size" was attempted to be placed on cruisers. Under the terms of the Washington and London Naval Treaties, these battlecruisers were considered capital ships, while the heavy and light cruisers had no restrictions on the number that could be built.

 

And it's a good point. Here's something else to keep in mind: the word "cruiser" does not appear anywhere in the Washington Treaty. Neither does the word "battleship," for that matter. With battlecrusers absorbed into the capital ship category, the bifurcation of the cruiser type was complete, and the stage was set for the hybridization of battleship with battlecruiser. If anyone is interested, I give scrutinize the cruiser and cruiser terminology in my booklet In the Shadow of the Battleship (ISBN-10: 1934840521 ; ISBN-13: 978-1934840528).

 

I believe "cruisers" in WW1 were ships with enough endurance and size to be capable of independent operations while torpedo boats and destroyers were generally uncapable of that and lacked the range for them.
After WW1 the distinctions gets blurred as destroyers grew from less than 1000 tonns to 2000 and more, but still mostly operated as flotillas for mutual protection as a destroyer flottilla could, and often did, overwhelm an isolated cruiser and provide massive AA fire.

The main reason for a fleet's existence is to get convoys through, and prevent your opponent's from doing so, you will generally have:
- Convoys escorted by "escorts" against submarines and aircraft. Fleet destroyers are usually unsatisfactory escorts as they were optimized for surface action while the main threat was air and subs. Also the high speed (35+ knots) of fleet destroyers is not very useful for escort work where range is more important so specialized escorts were used by most nations.
- A close escort composed of cruisers, with possibly some long legged fleet destroyers attached, was provided if strong opposition was expected. If the convoy had to travel through areas with strong enemy air opposition cruisers, especially if of the AA type, would actually sail with the convoy, and some navies even added an escort carrier to the close escort, but generally admirals preferred not to tie the heavy ships too closely to the convoys.
- A remote heavy support group with battleships and aircraft carriers in case an enemy major force is expected, this group may actually never leave port unless the enemy is spotted so as not to expose the capital ships to attrition by subs and aircrafts.
The above pattern is the usual one and shows the most common usage of the various ship types though there where plenty of exceptions. Mechants and escorts do the everyday work while the heavy ships mostly sit in port unless committed to a major effort. Cruisers are an "in between" type that are committed were strong opposition but not a major effort is expected.
For the "sea denial" role the picture is slightly different, interception or raiding forces may include any warships with sufficient range and speed an admiral can lay his hands on but capital ships were usually only risked in exceptional circumstances.

 

TiredOldSoldier could you give me an example as to what kind of ship was preferred to be used as the "convoy escort"? This is the role you mention included ASW but fleet destroyers were unsuitable for.

 

The best convoy escorts for anti-sub duty were the frigates. These had excellent range, good seakeeping, and adequate speed. Off the top of my head, British mercantile-type frigates were the only ships to carry the Squid weapon. Destroyer escorts were nearly as good; their range was not as great as a mercantile frigate's, but it was still adequate. Speed was generally better, which allows a better opportunity to respond to sightings/soundings. Seakeeping was not as good, and none of these ships carried Squid.
Some writers will claim that the "Flower" class corvettes were the decisive weapon in the war, which may be overstatement but deserves some consideration. These were less capable in all regards, but they were present in large numbers from an early date.

 

I used the generic word "escorts" on purpose as each navy called them differently.

Britain had frigates (the best), sloops and corvettes and the Hunt class escort destroyers that were a bit of an anomaly as they were optimized for AA rather than AS work.
The USA had several destroyer escort classes (DE).
Italy had torpediniere di scorta (escort torpedo boats) and corvette (corvettes)
Germany did not really build any escorts, they had no "blue water" convoy routes so mostly used R-Boats and Flak ships (old cruiser hulls or mechant conversions with lots of AA guns mounted on them) to protect them. Their torpedo boats were conventional designs of aroound 1000 tonns with 9 torpedo tubes and little else so not very good for escort work.
The japanese built "Escorts" roughly comparable to small frigates.
The French had the "600tonn" Torpedo Boats (actually >700t) and a 1100 tonn design in the works that both look more like "small destroyers" rather than true escorts.
Despite the naming we have really only two ship types.
The frigate/DE/escort torpedo boat that was a warship hull capable of 25 to 30 knots and armed with 2 to 4 guns of 3' to 5' caliber (most had 4'), lots of light AA guns and depth charges in both racks and throwers and sometimes an advanced ASW weapon like squid or hedgehog. Displacement was from 700 to 1200 tonns with most being around 1000.
The corvettes were derived from civilian hull types of around 600 tonns and could not sail faster than 25 knots, they carried one main gun and as many depth charges as they could cram on it plus some light AA pieces. It was an emergency measure as they was cheaper and faster to build and operate than a frigate and just big enough to be able to tackle ocean waters but not really as effective as a frigate/DE.
To make thing more confusing the designation sub chaser was also used sometimes for some particular ships but was very uncommon and most ships with that designation were "one of a kind" not mass produced classes like the escorts tended to be. Most sub chasers were really prototypes built in the search for an ideal escort design and could be classed as frigates/DE though on the smallish side.

As an aside after the war the USN started calling 8000 tonns ships frigates before "seeing the light" and reclassing them as the cruisers they really were .

 

You have inadvertantly answered another poser I had beentrying to remember the details of. Wether or not a system called squid existed before/alongside hedgehog!! Thanks for that and the other info.

 

That part seams off a bit. I can't think of any Frigates that were reclassified as cruisers. The original Aegis ships were build on an extended Spruence type DD hull and reclassified as cruisers. The Frigates of the time were the Oliver Hazard Perry class weighing in around 4,000 tons.

 

I believe TiredOldSoldier was refering to the perceived Cruiser Gap. In 1975 the USN reclassified it's ships due to the fact that Russia had a diffrent way of classifying it's ships. On paper, when comparing the Soviet Navy to the US Navy, the US Navy had half the number of cruisers the Soviets had. In actuallity the US frigates where equall or superior to the Soviet cruisers. At least the first two ships of the Ticonderoga class where origionaly classified as destroyers, and the first three ships of the Virginia Class where classified as frigates.

 

The US-built frigates carried the long 3in gun, as did the early destroyer escorts. "Frigate" requires some qualification in its RN application, as they applied it to both mercantile designs and to the American destroyer escorts.

 

You need to go back a little more .... The post war Leahy and Belknap classes, plus the nuclear powered Bainbridge and Truxtun were launched as "guided missile frigates" and classed as (DLG/DLGN) but were later reclassified as cruisers (CG/CGN). (Source Jane's 1975-76), at the time the escorts were still called DE not FF so there were no other frigates in the USN.
The Britsh River class and later ships are a hybrid of merchant and warship construction standards but I must admit they blur my classification as they mostly fit my definition of corvettes but are called frigates by the RN.

My mistake for the ' instead of '', I am more used to metrics US DE had either 3inch or 5 inch guns most other countries 4 inch or 100mm which is about the same.