The Cruel Sea:
German Aircraft Carriers

Our The Cruel Sea expansion set is the centerpiece of our Second Great War at Sea alternative history setting, taking place in a world where the First Great War ended with a negotiated settlement in December 1916, allowing the great empires to last for another generation and fight another war starting in 1940.

The set is focused on the Imperial German Navy, and also includes French and Imperial Russian ships and aircraft. The Second Great War sees a different emphasis on aviation technology, without the developments of the last two years of the Great War to influence inter-war advances. Lighter-than-air and rotary (helicopters and autogyros) flight are much more important than in our own history. And aircraft carriers do not receive the early impetus seen in the last days of the Great War.

Yet there are still aircraft carriers! My friend Kristin Ann High pointed out to me some time back that a carrier air establishment requires a relatively massive investment in infrastructure in order to produce pilots, suitable aircraft and a doctrine for their use. And that has to be considered when crafting an alternative-history setting. If you just add big fleet carriers to your alternative navy without explaining from where they came, then you might as well toss in Godzilla, too.

Nazi Germany and Fascist Italy did not make that investment, and therefore their programs resulted in no operational aircraft carrier ever taking to the seas. Imperial Germany in our setting has ventured toward that investment, but unlike the Royal Navy across the North Sea they have not gone “all in” for the aircraft carrier.

The High Seas Fleet of the Second Great War includes but two true aircraft carriers. The training carrier Ausonia is old, slow and carries few aircraft, but she does indeed carry aircraft. She’s based on actual German plans from 1918 to convert the incomplete liner Ausonia, ordered by an Italian firm in 1914, into a full-decked aircraft carrier.

Over the years that have followed she’s been somewhat modernized, starting with her power plant as early experiments showed the difficulties of operating a coal-burning aircraft carrier. Her flying-off deck originally mounted forward has been removed and her flight deck extended to the bow.

The original Ausonia design called for two hangar decks, one above the other, both above the main structural deck. The lower deck would carry seaplanes and the upper deck wheeled aircraft. That would have placed the ship’s center of gravity very high, and it’s likely that one hangar deck would have been removed, probably during the design phase.

As found in The Cruel Sea, Ausonia has one hangar deck, allowing her to operate sixteen to twenty aircraft, as from her initial design a mix of biplane fighters and torpedo planes. She is terribly slow and best suited to the training mission, but will see some action as a convoy escort as she can also operate helicopters or autogyros at need.

The second aircraft carrier is another converted liner, based on the hull of the much larger passenger ship Columbus. Laid down in 1912 at the Schichau yard in Danzig for the North German Lloyd and launched in December 1913, Columbus was laid up incomplete in August 1914 with the outbreak of war – amazingly, the German government did not actually require that work stop on the liner, but Schichau received higher-priority military contracts that tied up all of the shipyard’s labor force (work continued on other civilian projects including Ausonia, under construction at Blohm und Voss in Hamburg, and she was launched in April 1915, eight months after the outbreak of war, and only stopped when Italy declared war on Germany a month later).

Columbus had a number of modern features – an outdoor swimming pool, and a topside deck for nighttime dancing under the stars. But she had been designed with old-fashioned triple-expansion engines rather than turbines, giving her better fuel efficiency at the price of a much lower speed (18 knots) than other liners and this would have been a problem for the North German Lloyd had they attempted to use her on the speed-conscious North Atlantic passenger run.

Note: The real liner Columbus would be completed by Schichau after the war amid a great number of work slowdowns and outright sabotage, and handed over to Britain as a war reparation where she served as the White Star Lines Homeric. She retained her triple-expansion engines and coal-fired boilers, as the new owners did not want to delay delivery nor incur the expense (the old power plant was included as a reparation, but they would have had to pay to replace it).

The Imperial Navy could have bailed out the Lloyd by taking over the incomplete liner and converting her into an aircraft carrier along the lines of Ausonia, but much larger (35,000 tons’ displacement, compared to just 12,500 for Ausonia). She would have needed new, oil-fired boilers and turbines to raise her speed and do away with the heavy clouds of coal smoke that would have limited air operations. And it’s likely that construction would have proceeded slowly, so that lessons learned from Ausonia could be incorporated into the new ship.

As an aircraft carrier, Sleipnir as we’ve named her carries a substantially larger air group than Ausonia, probably 50 to 60 aircraft. With her new and improved turbines she boasts a much better speed than the older carrier and is fast enough to operate with the battle fleet. But the High Seas Fleet has not invested a great deal of effort into developing carrier doctrine; there have been paper exercises but the carrier has rarely operated with the fleet.

The High Seas Fleet has invested its resources instead in lighter-than-air and rotary flight. The big airships with their “parasite” aircraft can perform the reconnaissance mission far more effectively than the carrier; Sleipnir’s torpedo planes carry a potentially decisive punch but their short range makes them little more effective than destroyers in delivering a torpedo attack, at least according to most naval planners.

A growing emphasis on autogyros and helicopters would have also limited training time for the fixed-wing element as the carriers helped prepare pilots for sea duty. These aircraft could perform far more effectively in the anti-submarine and mine-hunting roles than the biplanes, with only slightly less range. They could not deliver the same effect in the strike mission, but the High Seas Fleet put little confidence in its carrier torpedo squadrons.

As true helicopters became available in the 1930’s, replacing autogyros, the High Seas Fleet sought dedicated platforms for them. While most large warships now sported helicopter pads, with some having rather elaborate hangars, they could not provide the repair and maintenance facilities of a dedicated helicopter carrier, and had other missions to fulfill.

The Siegfried class is a compromise design, with a cruiser’s main battery forward (two dual gunhouses for 150mm guns), a cruiser’s speed and a large helicopter deck aft. She has two hangars, one amidships at the main deck level and another under the flight deck. That provides enough space to not only operate her own squadron, but to provide support functions for helicopters assigned to other warships.

She’s less capable than a through-deck ship like the big Russian helicopter carriers, and in practice the masses of fuel and munitions carried under very lightweight armor make the use of the guns in surface combat a risky proposition. But she does make for a very capable convoy escort, able to put multiple helicopters into the air very quickly, and she’s also large enough to operate the big transport helicopters of the Imperial Marines, making her useful as an assault ship as well.

Notes: The Siegfried design is roughly based on the British helicopter support ship RFA Engadine, which was built in the mid-1960s and saw action during the Falklands War.

Helicopter support ship RFA Engadine.

And that’s the Imperial German carrier contingent from The Cruel Sea. We’ve tried to follow typical design practice of the period, basing the true carriers on the actual Ausonia design and the specialist helicopter carriers on an actual design of the 1960’s, a period when helicopters began to see the same widespread deployment in our world as they enjoy in the timeframe of the Second Great War.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and award-winning journalist, he has published over 100 books, games and articles on historical subjects. He lives in Birmingham, Alabama with his wife, three children and his dog, Leopold.