Iowa Class Battlecruisers? Were America’s most Powerful Dreadnaughts actually Battlecruisers?

iowa class battlecruisers

Iowa Class Battlecruisers? Were America’s most Powerful Dreadnaughts actually Battlecruisers?

By: Chris Knupp

On the surface, history can appear a rigid, unmoving thing. That once something is historically established, it remains that way forever. However, the truth of the matter is that history is largely pliable. The more blurry facts can be easily be bent to support a particular view. A small, but popular opinion is that the Iowa class battleships of the US Navy could be considered battlecruisers. What are battlecruisers and why would anybody think the Iowa class is like them? I will look at the rationale for this opinion and refine the lines that separate battleship from battlecruiser. With a bit of digging, we will find out whether we need to refer to these dreadnaughts as the Iowa class battlecruisers from now on.

Why would the Iowa class be considered Battlecruisers?

I have found two prevailing arguments in favor of classifying the Iowa class as battlecruisers.

1) Their armor was unable to withstand the firepower of their own guns.

2) They sacrificed armor to achieve higher speeds.

It is true that these ships were exceedingly fast and that armor wise they were a departure from traditional practice. However, is this enough to brand them as battlecruisers? To compare, let us examine the concept behind battlecruisers and see what made them different from battleships.


What Are Battlecruisers?

iowa class battlecruisers
HMS Hood, the largest battlecruiser ever built. Her weak protection became her undoing in her famous fight against the battleship Bismarck.

Battlecruisers were a short-lived vessel only used during the first half of the 20th century. They were conceived on the idea that faster capital ships would be both more effective and more flexible than the slower battleships in combat. Battlecruisers were designed to fulfill the following criteria:

  • Use their superior speed to chase down slower vessels.
  • Outgun weaker vessels while being able to outrun more powerful ones.
  • Harass enemy shipping lines and disrupt trade.
  • Support the main fleet by defending against cruisers.

To achieve these objectives, battlecruisers were designed for maximum speed. They achieved this speed by sacrificing armor, firepower, or a combination of the two. For the most part, battlecruisers were designed for speeds greater than 25 knots while the slower battleships were only capable of 21 knots.

At first, battlecruisers were fairly effective when deployed in the manner in which they were intended. The Battles of Heligoland Bight and the Falkland Islands were instances of battlecruisers fulfilling their roles and destroying enemy cruisers. However, as the war progressed, battlecruisers became increasingly less useful. Coordinated actions by large fleets ensured that they were only as fast as he slowest vessels involved. In latter engagements like the battle of Jutland, they fared poorly when forced to directly engage the more heavily armored battleships.

To rectify these weaknesses, cruisers became increasingly armored to the point that they were almost battleships. On the other hand, battleships were becoming faster, to the point that newer designs were as fast as battlecruisers. These advances caused the line between battleship and battlecruiser to blur.

Are the Iowa Class actually Battlecruisers?

At first glance the Iowa class vessels were very similar to battlecruisers. They were directly designed to hunt down and destroy weaker ships such as the Kongo Class battleships. They were lightly armored compared to their displacement, especially compared to previous US battleships. However, they also were very different in several important areas. First, lets take a look at some of the arguments listed above.

Their armor was unable to withstand the firepower of their own guns

On the subject of a vessel being armored to withstand the firepower of its own guns, this was never a method of classifying battlecruisers.  No ship is armored enough to be completely impervious to its own guns. Even the mighty Yamato was vulnerable to its own guns at certain ranges, but that does not make it a battlecruiser. Most ships are designed to be immune to large caliber shells at certain ranges, normally those that combat is expected to take place. This is what’s known as an immunity zone.

While the Iowa class did have an immunity zone against its own guns, it was smaller than US designers would have preferred. This was largely due to advances in technology. The Iowa class was originally designed to withstand the US Mark 5 2240lb AP shell. The designers were able to create  reasonable zone of immunity from this shell. However, after the designs were largely finished, the Mark 8 2700 “Super Heavy” shell was introduced. This shell offered much greater capability and was thus harder to protect against. When combined with the 16″/50 cannon, the Iowa class had what could be the best naval gun put into service. At long ranges, the cannon was almost equal to the Yamato’s larger 18″ guns. Armoring against this shell would have required a much greater displacement than what the Iowa class offered.

As to the idea that battleships must be armored to resist their own guns, As best as I could tell, this myth arose from the practices of naval designers when creating armor schemes for their warships. Not having access to foreign weapons, they used their own weapons. Thus, they designed their own ships to resist their own guns. It was simply a matter of convenience.

They sacrificed armor to achieve higher speeds

iowa class battlecruisers
The heavy 17″ armor used to protect the conning tower of the Iowa class.

This myth is untrue, though it does unveil some rather interesting details.  While the designers never sacrificed armor when creating the Iowa class, they also didn’t go out of their way to add more armor. As stated above, they did work to ensure that the class was armored to withstand its initial shells. However, the preceding South Dakota was sufficiently armored as well. In fact, the armor scheme of the Iowa class was directly based on the South Dakotas with some minor improvements.

While the Iowa class might not have been armored as much as US designers would have preferred, it was still very much a protected battleship. It was designed to engage battleships in direct combat, survive whatever shells came their way, and emerge the victor. This is a stark contrast to the types of combat that typical battlecruisers were to engage in. At the very least, one could make the argument that the Iowa class was a faster model of a preceding battleship.

Conclusions: Battleship or Battlecruiser

Based on design and the intentions of designers, the Iowa class were battleships. They were designed like battleships, they were armored like battleships, and they could certainly fight other battleships. However, I would go so far as to argue that their design was unique. Perhaps a blend of ideas behind both battleships and battlecruisers to a degree.

As battlecruisers gained armor and battleships gained speed, the line separating the vessels blurred. The Iowa class exists in that blurry area. It was a battleship that incorporated some of the doctrine that inspired battlecruisers. Unlike battlecruisers that were designed to chase down and destroy enemy cruisers, the Iowa class was designed with bigger prey in mind. They were designed to hunt down enemy battleships and other large vessels. Unlike battleships, that got faster through the advancement of engine technology, the Iowa class was designed to be fast. They were the only class of battleship that could be considered true fast battleships in that speed was a main goal in their design.

In many ways, the Iowa class took the best features of both battleships and battlecruisers to create a specialized class. The real question is what the Iowa class would have inspired had the age of dreadnaughts not ended when it did. How fast would have subsequent battleships become? Unfortunately, we will never know.

If you would like to check out more of my articles, you can access the entire collection here at my personal website


Chris Knupp

A student of military history, I am working to make history more interesting and accessible for everyone.


  1. You’re acting as if fast Battleships weren’t a thing before Iowas. Bayern and Queen Elizabeth (or arguably Kaiser and Koenig classes) started the idea that battleships could be fast much earlier, with the US standard classes being slower for a long time. US armouring schemes were also not focused on armouring the whole (or even arguably most) of the ship to begin with. Simply, this is a pile of clickbait, far too short to present meaningful arguments, and came to a forgone conclusion.

    • Thank you for the comment.

      To start, while the term “fast battleship” has been in use since the Introduction of the Queen Elizabeth class, you have to remember that battleships were getting faster because the machinery was becoming more powerful, not because the designers were going out of their way to make a fast battleship.

      The Queen Elizabeth class established such a high speed that they got to set the bench mark. Any later battleship that exceeded that speed got labeled a fast battleship as well. This is why even battleships like the Yamato got to be called a fast battleship despite speed taking a backseat to armor and firepower.

      On the subject of US Battleships, you are correct in stating that they were slower than the norm for some time. US Naval doctrine always emphasized armor and firepower over speed. Even the North Carolina and South Dakota classes, despite being “fast battleships” due to their 28 knot speed, were the slowest of the designs chosen by US designers.

      The Iowa class battleships were the first designs by the US that emphasized the need for high speeds. Essentially, 10,000 tons was added to a South Dakota class design just to attain 6 knots and slightly more powerful main guns. Many senior US naval designers were actually unhappy with the designs due to a lack of armor. The following Montana class would have been a return to traditional US design practice of armor over speed.

      I don’t know what you mean by US armoring schemes were not focused on armoring the whole of the ship. Every navy adopted the “all or nothing” armor scheme just like the US. Therefore, only the most critical areas of the ship were armored.

      Even with the Iowa’s “lighter” armor, they still achieved several things that other navies could not.
      1) The ship was designed so that its citadel had enough protected buoyancy to keep the ship afloat even if the void spaces were flooded, unlike the Bismarck.
      2) The Iowas had heavier transverse bulkheads on each end of the citadel than all other ships except for the Yamato. This means that the magazines were well protected from raking fire from the bow or stern.
      3) The scheme of the Iowa was designed to ensure that even penetrating shots through the bell were still shattered and thus more ineffective, a feature most other navies were never able to achieve.

      Lastly, the length of my articles is completely dictated by whatever website wishes to publish them. This is a brand new website and to make it grow, I need the support of larger websites. When the day comes that I can rely on organic visitors and I am not restricted by other websites, I will be more than happy to publish much longer articles.

      I hope this addresses some of your issues and once again I thank you for the comment.

      If you would like to talk further or have ideas for improvements, hit me up on the forum. You obviously know your ships and any input would be welcome.

  2. While you are correct in stating the Iowa’s were designed to combat shipping and other warships directly, the main reason for the high speed design was to keep up with the newer carriers, which could achieve greater speeds than previous battleships. It was projected that, with superior fire control computers and radar, armor was not as necessary as speed. So I do see the connection between battlecrusier and battleship for the class, but the tonnage of the class when fully loaded (57,000+ tons) also classifies it as a battleship.

    I currently work as a Docent on the USS Iowa in San Pedro, CA. I really enjoyed your article and the points you made. Have you visited any of the Iowa’s since they all became museums?

    • Hello Nate,

      Thanks for the kind words and I am happy you liked the article.

      You are right to state that the Iowa’s speed made them suitable for escorting carriers. However, the original design was not to escort the carriers against aircraft as they ended up doing.

      Rather, they were designed to protect carriers from enemy battleships, specifically the Kongo Class. Enemy ships that were too fast for main fleet to effectively bring to battle. US planners feared that such ships could bypass the slow US battleships and smash the through the cruiser screen, directly striking at US carriers.

      Once carriers established themselves as the centerpiece of the fleet, the Iowa class found new use as heavy escorts since they were the only US battleships fast enough to keep up with the carriers.

      As for the battlecruiser element, tonnage never differentiated between battleship and battlecruiser, only intent behind the design. The Iowa class were battleships, however they incorporated some battlecruiser elements in that they were designed for high speeds and to hunt down opposing ships away from the main battleship fleet. They were true fast battleships and thus different from both standard battleships and battlecruisers. The ultimate culmination of both if you will.

      On the subject of armor, I would have to disagree. The US was still very much in favor or heavier protection as evidenced by the Iowa class successor, the Montana class. Even after the Second World War, the US was proposing several modifications to the Iowa design to strengthen protection at the cost of speed.

  3. The only Battle Cruisers that the US built (the Alaska Class) were more of a light battleship. They were more heavily armored than traditional BC’s keeping with US doctrine on armoring ships.

    • The Alaska class were really enlarged Baltimore class heavy cruisers. They were neither cruisers nor battlecruisers but a design originally created for the single purpose of hunting down the German pocket battleships.

      One of the early designs for the Alaska class was a “mini” battleship. Roughly 38,000 tons and armed with 12x 12″ guns. Would of been interesting to see the design had it been chosen.

  4. Chris,
    Enjoyed your article. Having served aboard her in the early 80’s your article was appreciated and a good trip for the memories.
    Hope to get out to San Pedro soon. But being in Virginia it’s nice to have a sister ship nearby.

    • Hello Tom,

      Thanks for the kind words. Its always nice to hear from those who experienced the ships first hand. Hopefully you can drop by the forum and recount some of your experiences.

  5. Chris, I also read you essay about the Alaska class, which in its conclusion you said both the Iowa’s and the Alaska’s were hybrid ships. In my strictly amateur opinion you hit the nail on the head. That is why it is difficult to classify these two ship classes.
    Your goal of making history more interesting and accessible is working with this long time WW2 history buff.Thank you.

    • Hello Matthew and thank you for the kind words. With the Iowa and Alaska class, the US designed each ship to fulfill very specific roles. This led them to be very unique vessels that ended up being extremely effective. Among their peers, both ships had no equals.


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