Tre Kronor:
German Coast Defense Ships
by Mike Bennighof, Ph.D.
March 2023

To craft the world of the Second Great War, the setting of Second Great War at Sea: Tre Kronor, The Cruel Sea and other Second World War at Sea alternative-history expansions, I got to create not only the fleets and air forces of the nations involved, but the politics that shaped those fleets.

In our own reality, five naval powers reached an agreement in 1922 to limit the escalating arms race among them. Concerns over the vast cost of ever-larger battleships, as well as a desire to limit the potential for future wars, drove Britain, France, Italy, Japan and the United States to reach the modern world’s first arms control treaty. The treaty left loopholes, which every signatory sought to exploit.

In the world of the Second Great War, a naval conference held in Vienna brought all ten naval powers to the table, split into five classed as first-rank (Germany, Britain, Russia, Japan and the United States) and five as second-rank (Austria, Italy, France, Turkey and the Netherlands). The treaty limited the size and armament of battleships and cruisers, and the number of battleships that could be laid down in one fiscal year.

While the number of battleships – an offensive weapon – would be limited, no limit was placed on the number smaller vessels that could be built, including coast defense ships armed with heavy guns. While signatories could build any number of them, they were initially limited to 12-inch guns (later raised to 15-inch weapons) and 12,000 tons (later increased to 17,500). A meaningless clause also limited their speed to 21 knots, but even at the time this was understood to be unenforceable.

Wing 305mm turret of SMS Ostfriesland.

The High Seas Fleet had decided to scrap the old battleships of the Nassau and Oldenburg classes even before the war ended. Their lack of speed held back the battle line and could easily have led to disaster at Jutland. One (Helgoland) would be retained as a training ship, but their out-dated triple-expansion engines and old-fashioned “hexagonal” turret layout made the others expendable. Replacing their power plants and drive trains would have been far too great an investment for a marginally-useful ship. As the cutting torches tore apart the ships, their weapons went into storage, including their main gun turrets and armored barbettes. That left 22 305mm turrets and 24 280mm turrets.

When the completed Vienna agreement came into force, those weapons became a resource, allowing the High Seas Fleet to build a large number of coast defense ships at a reasonable cost. The High Seas Fleet ordered six ships in the 1924 fiscal year, and then five more in 1926. A further two units were ordered in 1932, using turrets removed from the König class battleships during their modernization.

The new Cherusker class, named for ancient Germanic peoples, displaced 12,000 tons and carried four 305mm guns in the Model 1908 turrets taken from the old dreadnoughts, modernized for much higher elevation and improved overhead protection. They carried four 150mm guns in a pair of twin turrets, one on either side, four 105mm heavy anti-aircraft guns, an array of light anti-aircraft weapons and four torpedo tubes, two on either side.

They’re based on an actual design presented to Admiral Hans Zenker, commander of the Weimar Republic’s Reichsmarine, in the 1920’s. That ship would have been diesel-powered and made 25 knots, where this version has conventional oil-fired steam boilers driving turbines for about 22 knots. She has good protection, but is only intended to operate in coastal waters so she doesn’t have the range to operate in the Atlantic. The original design had an additional turret for 150mm guns and more heavy anti-aircraft, but with conventional steam boilers the ship needed a smokestack, and she’s added a helicopter pad while the Weimar proposal operated no aircraft.

While a handsome and well-designed ship, and inexpensive to build, her utility in wartime has to be questioned. She’s not fast enough to run away from anything but the oldest Great War-era dreadnoughts, though she has the heavy guns to drive off enemy cruisers. The 305mm L/50 is an excellent weapon, but out-ranged by the 15-inch and 16-inch guns carried by almost all enemy battleships.

When war erupts in 1940, four of these ships are stationed in the Baltic Sea, where they’ve been employed as training ships. Five are based at Dar es Salaam in German East Africa, and the final four at Rabaul in German New Guinea.

305mm turrets of the dreadnought SMS Kaiser.

Impressed by the low cost of the “new” ship, Germany’s Ottoman Turkish allies ordered 10 of them to a similar design but equipped with the 280mm turrets taken from the Nassau class and modernized along the same lines. These formed the centerpiece of new squadrons stationed in the Red Sea and the Persian Gulf. Bulgaria bought two of them to form the heart of the revived Royal Bulgarian Navy.

The older coast-defense ships have little to no hope of fighting enemy battleships or even cruisers, but were very inexpensive to build and are inexpensive to maintain. That makes them perfectly suited to the training mission, and with the Imperial Navy taking in thousands of conscripts every year and giving refresher training to an even larger number of older reservists, the High Seas Fleet has a great need for training ships. On overseas stations, the coast defense ships allow the Navy to show the flag at relatively low cost and are usually only opposed by older ships relegated to distant stations by other colonial powers.

Their relatively shallow draft combined with the heavy guns suits them for shore bombardment, and this mission is where they see the most action during the Second Great War. The Central Powers have kept the Russian Baltic Fleet penned into the Gulf of Finland, and the hard-pressed German Army and its allies need all of the help they can get against the relentless advance of the tsar’s armored forces. There the coast-defense ships really can replace true battleships, with two or three such ships providing equal firepower without detracting from the battle fleet’s strength.

In Turkish service, the even-more-weakly armed ships had the great value of their low cost. They allowed the Empire to create new, badly-needed squadrons on its periphery without detaching its limited number of modernized heavy ships and modern cruisers from the main fleet based at Constantinople.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and NASA Journalist in Space finalist, he has published a great many books, games and articles on historical subjects; people are saying that some of them are actually good. He lives in Birmingham, Alabama with his wife, three children, and new puppy. He misses his lizard-hunting Iron Dog, Leopold.

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