U1 class

New Cycle ! SMS U1 was the first in a short line of Austro-Hungarian submersibles (27 in all) prior and during WWI. Austria-Hungary started to enquire about these in 1904, but it’s really by 1906 that was started the first class, built at home, but from plans licenced from US naval engineer Thomas Lake. Their original gasoline engines were an issue, later replaced by modern diesels. Diving procedures were particularly complex, amounted to eight minutes. Therefore, they never saw action, being relegated to training in Pola until January 1918, and then decommissioned. They were ceded to Italy in 1920, which had them broken up presto. Hopefully, the next pair would be also a Lake design, but built in Germany…

U1 underway in Pola. Although she had a 37mm Hotchkiss deck gun in 1917-18 it was almost never shown in her rare photos.

Development

By 1904, the Austro-Hungarian Navy, wich ambitioned to take the lead in the Adriatic, had all the panoply of a modern navy at that stage, with pre-dreadnoughts and even its first dreadnoughts planned, all sorts of cruisers, destroyers and torpedo boats or gunboats, but no submarines, or “submersibles” would be more appropriate for this day and age. The naval staff at the Naval Section of the War Ministry (Marinesection) in Vienna, at the gigantic, baroque Ministry building and its administrative offices at Vordere Zollamtsstraße, was fully aware of foreign naval developments, following naval reviews of the time such as Brasseys and Janes, which had German editions. They knew about developments in the US, from Lake and Holland, saw USS Holland being commissioned and positive reviews, they saw adoption under licence of the design by Vickers, and the Holland design rapidly spreading.

A skeptical Staff… until 1904

However, in 1904 Vice-Admiral Count Rudolf Montecuccoli (still in office by 1914) recently elected along with the establishment of the Austrian Naval League in September, doubted, based on hydrographic works performed already by Austria in the Adriatic back in the 1870s, that this sea would be problematic to submarines, in addition of being costly and complex to operate compared to traditional torpedo boats. Perhaps he refrained to draft a proposal to submit to the parliament (Országgyűlés), split between the Austrian (Cisleithania) and Hungarian half (Transleithania). Given the latter, as usual, was likely to deny these funds for a “hazardous and costly innovation”. In addition, their northern German-speaking Imperial neighbour’s Imperial Naval office head, Alfred von Tirpitz was also highly dubious of submarines despite enthusiast officers and Prince Henry of Prussia himself.

So the incentive was not there before 1904, at least at the head. No doubt younger officers were more enthusiasts, notably as a more clever way to dispense torpedoes, after all invented in Croatia. However Montecucoli’s expansion program was even more ambitious than his predecessor’s, Admiral Hermann von Spaun, pushing for a greatly a modernized navy, and thus intended to gradually introduce submarines as well eventually. If there was anything to further stir things up, that was what Italy did on the other side of the Adriatic. And indeed, Italy had already a its first operational submarines: Delfino was already tested from 1892, Glauco was planned to be launched in 1905, and it was especially the latter that really started to worry some in the naval staff.

The KMT Competition and its Reset(1904-1906)

So by 1904 Generalschiffbauingenieur Siegfried Popper, ordered the Naval Technical Committee (MTK) to look for an existing design to purchase, and a competition was open after specs were published on 17 January 1905. Eventually the committe retained three proposals from yards, with two submerined to be built for each. All three were relatively similar in size, displacement, but not so for technology and capabilities.
It should be also stated that all domestic proposals were rejected by the Navy. However technical problems during the initial design phase delayed further proposals from MTK for about a year, into later in 1905. In between Montecuccoli secured these submarines, when he published his plan Montecuccoli by early 1905 for no less than 12 battleships, 4 armored cruisers, 8 scout cruisers, 18 destroyers, 36 high seas torpedo craft… and 6 submarines.

Lacking experience it was easier to gain it by studying various foreign designs and Lake’s proposal looked the best albeit the Marinesektion remained skeptical about their seaworthiness. The goal for these six subs, was to compete against each others to determine the best for a large production. The base specs were for a 22.1 meters (72 ft 6 in) for 3.6 meters (11 ft 10 in) and 4.37 meters (14 ft 4 in) daft submarine dispplacing no more than 134.5 metric tons (132 long tons) when surfaced, which was extremely precise. But it appeared just too small and the boats from Simon Lake, Germaniawerft, and John Philip Holland were all a but larger as the first specs were deemed “unrealistic” forcing a revision of the specs and proposal.

U-1 was designed by American naval architect Simon Lake from the Lake Torpedo Boat Co. at Bridgeport, Connecticut. The company already had been contacted to take part in the MTK competition before it was scrapped. So it’s only by 1906 that the Navy formally ordered plans for building U-1 and U-2. In fact 1906, Lake traveled to Austria-Hungary in person to negotiate details of the agreement and the signing was done only on 24 November 1906. A complete set of plans was purchased whereas the Navy Yard in Pola was prepared. Plans were actually delivered, and preparations at Pola made to build this first submarine, the mosth technologically challenging and complex andeavour at the yard yet.

Design of the class

U1 was ordered on 24 November 1906, but only laid down un next July 1907 indeed and construction took time. She was only commissioned in April and her sister in June 1911. So six years total between preparation and operation, and already a refit in 1914. The Lake type dived deep indeed, but were not so great when surfaced, with a short range, had appeared later to have problematic gasoline engines poisoning the crew. Thus were born the first submarines in a limited serie of 27 operational, 63 planned. At some point there were far more German U-Boats than Austro-Hungarian ones at Pola in patrol.
Despite its limitations, the design impressed considerably Popper that went to say to Lake when meeting him:

“When I saw your plans I recognized that you had introduced valuable features that were better than mine, and also that you had actual experience building and operating submarines, so I went to the Emperor and asked his consent to substitute your type of boat for my own…Do you know, Mr. Lake, I have been responsible for the design of all other vessels built for the Austrian Navy during the last 25 years?”

Hull and general design

The U1 class was 30.48 meters (100 ft) long, for 4.8 m (15 ft 9 in) in beam and a draft of 3.85 m (12 ft 8 in). It displaced 229.7 metric tons (226 long tons; 253 short tons) surfaced and 248.9 metric tons (245 long tons; 274 short tons) submerged. Lake at that time designed double hull models, when MTK wanted only a single-hull type, but not with a torpedo-shape like Holland boats. Instead they had a full hull with a short keel, steep bow past the torpedo tubes, just below the waterline and short streight stem forward, and sloped down nose. The aft section underbelly was even sloping longer ip to the rudder’s frame. This was an utilitarian, rather ungaingly design. There was a flat deck that was utilitarian and all the way from the bow to the stern and two hatches, one forward, hindged communicatin to the pressure hull for reloading torpedoes or other large items. The second was just past the conning tower and round with a classic pressured shape.

However as it was experimental, and initially not made as a weapon of war, this Lake design also included a diving chamber, as well as wheels for traveling along the seabed, both for peaceful exploring. These were typical of Lake designs, a complication rejected by Holland. The idea however was seemingly adapted to the adriatic, with a lot of shallow areas. Some even believed that in addition to the torpedoes, the boat could enter an enemy harbour, “roll” to the seabed, and leave “frogmen” (that was still largely experimental by then) placing timed charges on the hulls of enemy vessels. The Italians just did that with their Mignatta in 1918 in Pola. The diving chamber was placed under the bow. It was also usable for the same commando missions, severing offshore telegraph cables and was a way to escape the submarine in case of a grave issue underwater.

In fact during sea trials, U1 crew realized their forgot to bring their lunches on board bfore staring a long underwater endurance test. A diver from shore carried the lunches in a waterproof bag, entering via the chamber. Lake’s retractable wheels was a way to stabilize the submarine while underwater, avoiding the keel to “stick” mud or sand. The diving tanks were unusually also placed above the waterline of the cylindrical hull, so that there was the need for a heavy ballast keel just for vertical stability. Flooding was done by modern electric pumps with a backup, but operation, if precise and loaded with options, revealed itself as cumbersome.

Powerplant

These had two variable pitch propellers, which was also a rare refinement for the time, and another innovation, that would not return for many decades. Initially, U1 and U2 were powered by two gasoline engines for surface running. This was completed by two electric motors while submerged. The gasoline engines were rated for 720 bhp (540 kW). The electric motors had an output of 200 bhp (150 kW). The model of the gasoline engine is uknown. The German used Korting paraffin models, but they proved equally troublesome. These gasoline units made for a top speed of 10.3 knots (19.1 km/h; 11.9 mph) when surfaced. When underwater as the electric engine were clutched on, best speed was 6 knots (11 km/h; 6.9 mph).

This contrasted with Holland boats at the time, better underwater. The operational rangehowever was the poor child of the design with only 950 nautical miles (1,760 km; 1,090 mi) at 6 knots (11 km/h; 6.9 mph) surfaced. It was still reasonably good underwater, 40 nmi (74 km; 46 mi), but only at 2 knots (3.7 km/h; 2.3 mph). In addition to the pitch propellers diving great flexibility and being two for extra aguility, the underwater steering comprised four pairs of diving planes, two forward and two aft close to the rudders. So this Lake design was quite agile.

Armament

Both were armed with three 45-centimeter (17.7 in) torpedo tubes: Two were in the bow, one in the stern (which was rared back in 1906) and they had enough internal spac for tow spares forward, so in addition to those in tubes, five total. However in general they only carried three. There was initially no deck guns planned. None was include in their 1914-15 refit but by 1917 a 37-millimeter (1.5 in) gun on a pintle was was bolted on deck of both boats, but removed in January 1918 when declared obsolete and back to training.

45 cm torpedoes

The model could be either Mark I or “Torpedo Fiume 1906” made locally at that time, having the same general caracteristics as the Whitehead Mark I, or more likely, the US 45-centimeter (17.7-inch) Bliss-Leavitt Mark 2 with a Compressed air reciprocating and dry-heater.
Specs:
1,900 lbs. (862 kg), body 197 in (5.004 m)
Warhead Mod 0: 207 lbs. (94 kg) wet gun-cotton, percussion or Mod 1 183 lbs. (83 kg) wet gun-cotton.
Two-stage turbine engine, alcohol fired dry heaters: Range/Speed 3,500 yards (3,200 m) at 26 knots.
Guidance: Mark 5 gyro.

37mm SFK L/23H

This licenced Hitchkiss light gun was only installed on both submarines from (unknown) in 1917 to January 1918. The 37 mm Schnellfeuerkanone L/23) was a light, quick-firing marine deck gun utilized by the Austro-Hungarian Navy (k.u.k. Kriegsmarine) and German Imperial Navy with barrel length of 23 calibers.
Specifications:
Caliber: 37 mm (1.46 inches). Barrel Length (L/23). Quick-firing single-barrel derived from the Hotchkiss system.
Ammunition: Small HE or frag shells. See the 1-pdr Hotchkiss for more.

⚙ specifications
Displacement	230t standard, 270t FL
Dimensions	30.5m long oa, 3.35m beam, 3.20 draft, see notes.
Propulsion	2 shafts 320 hp petrol engines+ 2x 100 hp electric motors (640/200 hp)
Speed	10.3 kts surfaced, 6 kts underwater.
Range	950 nm at 6 kts surfaced, 40 nm/2 kts underwater
Armament	2x 45 cm TTs, optional 37mm deck gun
Max depth	40 meters (130 ft)
Crew	17

A Short service for Disappointing Boats

The boats proved to be a disappointment. The diving tanks given their location on top of the cylindrical single hull and above the waterline, required a heavy ballast keel to provide vertical stability to be flooded by pumps for over 8 minutes. Furthermore, the gasoline engines were unreliable and never reached the contract power, so the Navy only paid for the hull and armament. In 1914 two new diesels were ordered to be placed instead. But nothing could be done for the diving, apart a more radical reconstruction. Naval historians David Dickson, Vincent O’Hara, and Richard Worth all wrote her out as “obsolete and unreliable when completed” “suffered from issues even after modifications”. René Greger even stated “the type proved a total failure”. This cale in stark contrast to Popper’s observation back in 1906…
Despite all this, U1 and U2 still brought very useful practical information for the Austro-Hungarian Navy, and Lake provided nothing less than what the Navy asked for. John Poluhowich in “Argonaut” recalls that at the time, Simon Lake completed them “to the satisfaction of Austrian officials”.

Lake was also satisfied of his design. He said after the trials (reported in his book “Submarine in War and Peace: Its Developments and Possibilities” (1918):

Our company had built the first two boats for the Austrian Government, U-1 and U-2. Another type of boat had been built later which had only a fixed periscope…One day, when this submarine was running along with her periscope above the surface…some officers approached in a speedy little launch and left their cards tied to the periscope without the knowledge of the commander of the submerged vessel. This demonstrated perfectly that it is essential, both in war and peace times, for the commander of the submarine to know what is going on in his vicinity on the surface.

The model, for the large picture was design to fit Austrian’s coastal defense, for close to shore patrols of the Adriatic but far less adapted in 1914 for offensive operations and quick raids on shipping.

Modernization

In 1914-15 both boats were drydock for partial reconstruction. Their length notably was extended to 30.76 meters (100 ft 11 in). The deck and bow casing was reconstructed in January 1915. More famously the hulls were gutted so to extract both gasoline engines, used on leased until then, and replaced them by diesels (Austrian origin), around May 1915 for U1, and March 1916 for U2. Final output was 640 hp combined, apparently the same output when checking the sources. No data is given indeed on the gasoline engine type or original output.
In 1917, both had a 37mm/20 SFK L/23 Hotchkiss installed on deck, only to be removed from January 1918, as they reverted to training. They also only carried their tubes torpedoes, no spares, so space could be freed for extra cadets.

SMS U1 was ordered from Marinearsenal or Seearsenal Pola, laid down on 2 July 1907, launched on 10 February 1909 and commissioned on 15 April 1911. Her first CO was Egon Marchetti, from there to 20 September 1911. Construction had been delayed by the import of the American-made engines, but after trials, they were found lacking and were kept only on lease, not purchase, until replacement by Diesels in 1915.

Calamitous Trials

Trials considerably delayed commission. They were performed during 1909 and 1910. A large part was expected, given their experimental nature. The Austro-Hungarian naval staff wanted indeed to test every possible aspect and scenario, so that a comprehensive report could be used for future design requirements. There was also an effort made to conceal them from the general public, especially Italy. The Austro-Hungarian government tried, but fauiled however to keep construction a state secret, and basically the same methods were used for the Tegetthoff-class battleships, far more visible. There were Italian spies and informants at Pola at the time. So Rome was quickly aware of them. On 13 October 1909, Montecuccoli addressed the Foreign Ministry about the urgent need to impose censorship restrictions on any trial results and this wacted upon by February 1910. When an Uruguayan naval officer visited Polan for example, he was denied access to a part of the yard, where the submarinese were parked, but granted access to the remainder.

However as the trials went, more and more technical issues surfaced, blamed on the gasoline engines. A common issue for these, also noted in early German U-Boats, was the toxic nature of the exhaust fumes and gasoline vapor that wer impossible to vent out correctly due to some limitations of the time and incorrect ventilations. These rapidly poisoned the air inside, increased the risk of internal explosion. This was trued also for the air admission inside the hull. It was apparently under-sized and using natural draft, so thre were just not enough air for combustion leading the engines to underperform. The contracted speed of 12 knots (22 km/h; 14 mph) which was great by 1906 standards, was never met. Instead, 10.5 knots was the best registered, and only for a short run as the crew was geting positively sick despite having the hatches open. The electric engines, also from the US, seemed deficient as well. Instead of the planned 7 knots (13 km/h; 8.1 mph) submerged the boats were one knot short.

The crews during these trials had to conduct frequent emergency resurfacing and in the end, these engines were simply considered unsuitable for wartime use. New replacement diesel engines were eventually ordered from the local Austrian firm Maschinenfabrik Leobersdorf, which accepted to lease the gasoline engines after extraction in their own facility under a a fee of US$4,544 annually. On 5 April 1910, U-1 had one serious incident when both electric motors were disabled by an accidental flood. The batteries were spared however but she needed to surface and get back to port anyway. Another damining test was the first submersion: It took 14 minutes and 37 seconds at first. In case of being spotted, surfaced, by an enemy vessel, she was dead meat. By working around procedures and techniques it was later possible to reduce to whole procedure to 8 minutes, but the initial technical choices for the ballast caused this.

U1 was tested under 40 meters (130 ft), but the hulls started to show great stress and deformations, busting pipes, etc. In short this was already close to crushing point. As a result, commission setup 40 meters (130 ft) as a limit for all future submarines. The four pairs of diving planes however gave them exceptional underwater handling, whereas the very precise ballasting system, which also caused so much diving time, could also lead to probably the best trimmed and balancing precision for 1909 worldwide, and they could be held within 20 centimeters (8 in) of the desired depth for example. While surfaced, however the upper shape of the hull, made for underwater performances, was frequently swept by seawater. The bow constantly dipping under, both “ploughed” heavily. As for the underwater wheels, thei used on the seabed proved to be almost impossible. The comparisons wit other designs was contrasted: They outperformed the Germaniawerft U-3 class and Holland U-5 class in diving and steering indeed. After these trials, she was commissioned on 15 April 1911 and U-2 on 22 June. Both models were the same so trials also brought about the same results.

Prewar Operations

Next commander was Otto Zeidler, and until 8 July 1913 Narciss Blessich. On 18 July, and until 2 May 1914 this was Franz Nejebsy and from 26 June 1914 to 17 December 1915 so until her refit, in waretrime, she was commanded by Klemens Ritter von Bezard. Between 1911 and 1913, U1 like her sister served as a training boat, intended to help later submariners given their known operational limitations. This was however bound to change in wartime. She conducted some ten training cruises per month until the war, showing at least it was reliable, despite the engines were still a pain for the crew. By late 1912 she was however mobilized as the Balkan Wars took place. By the end of November 1912, there was a war scare in the Balkans with Russia and Austria-Hungary mobilizing troops along their border as well as against Serbia. The Navy was fully mobilized and both were sent to the fleet assembling in the Aegean Sea. This subsided after the signing of the Treaty of London and U1 was demobilized on 28 May 1913. After this, she retunrned as a training vessel. However on 13 January 1914 near Fasana, she was rammed by armored cruiser Sankt Georg while underwater. Her periscope was bent and needed replacement.

Wartime Operations

As World War I broke up, U-1 was in drydock, awaiting installation of new batteries and diesels. To accommodate these she was gutted, and work proceeded for the swa until early 1915. I was disciovered that the new diesels and batteries needed extra space, so she was lengthened by about 11 inches (28 cm) for a displacement of 223 tonnes and 277.5 tonnes submerged. By early 1915, after trials she returned to training until 4 October. She was needed for locxal defence and stationed at Trieste on 2 November, to deter Italian raids or to bombard the port. Italian military intelligence know indeed of the presence of both U-1 and U-2 on regular patrol. From Trieste U-1 made also reconnaissance cruises until 22 December 1917. She was then reassigned to Pola. In between she had been commanded from 17 December 1915 after refit to 27 May 1916 by Franz Nejebsy, then Eugen Hornyák Edler von Horn until 13 September 1917. On 11 January 1918, under command of Othmar Printz (from 28 March 1918) U-1 was declared obsolete and only to act as semi-stationary training boat at the Brioni Island base. In mid-1918, U-1 was to be converted as an underwater minesweeper: Her diving chamber coulld indeed dispatch divers to severe anchoring cables of sea mines. This only remained a concept given U1 general state. Close to the end of the war in October 1918 she was sent back to Pola.

Fate

On the 26th of October, Austria-Hungary informed Germany the alliance was over while the Navy was a hotbed of ethnic and nationalist tensions. Mutiny was close. 3 days later, the National Council in Zagreb announced Croatia’s ties separated from Hungary but the provisional government not yet pronounced Independence so the fleet was given to its care. This was refused until it was placed also in command. Emperor Karl I agreed but also stated other nations could claim a share of the fleet in time. All sailors not of Slovene, Croatian, Bosnian, or Serbian origin were on leave, officers were given the choice of joining or retiring ans that also concerned U1. She was now part of the fleet to the State of Slovenes, Croats and Serbs instead of being handed over to the Allies on 31 October under Rear Admiral Miklós Horthy on his HQ on Viribus Unitis. The old flag was stuck. None new was raised.
Under the terms of the Armistice of Villa Giusti between Italy and Austria-Hungary on 3 November, the transfer of the fleet to the State of Slovenes, Croats and Serbs was not recognized and Italy sent ships to reclaim Trieste, Pola, and Fiume so by 5 November, Italian troops occupied Pola and on the 9th all remaining ships had the Italian flag raised, including U-1. Thus was confirmed later at the conference at Corfu by Allied Powers and the handover became formal on 10 November. U1 remained in custody, unmanned and un-maintained however as negociations went on and only in 1920 under the treaty of Saint-Germain-en-Laye she was ceded to Italy as war reparation. Given her state she was scrapped at Pola.

U2 had a very similar career to her sister, both had the same trials and fate. Laid down at Pola Navy Yard on 18 July 1907 she was launched on 3 April 1909 and commissioned on 22 June 1911. Her successive commanders were Klemens Ritter von Bezard from 22 June 1911 to 10 May 1912, Karl Edler von Unczowski from 10 May 1912 to 23 October 1914 (she was in drydock for modifications in August as the war broke out). She was returned into service under command of Otto Zeidler (until 15 February 1915). She had a second refit from January to June 1915. She ended 30.76 m (100 ft 11 in) long with new Austrian diesels and other modifications (see above). She stationed in Trieste on 7 August for active patrols and reconnaissance patrols, after training, deterring the Italians to raid the city, until until December 1917. By then she was under command of Otto Kasseroller until 13 September 1917 and then Johann Ulmansky von Vracsevgaj from 13 September.

By 11 January 1918, she was relocated for training on the Island of Brioni. On 15 March 1918 her new CO, Othmar Printz, took command but was also declared obsolete and by mid-1918, her conversion as a minesweeper, was considered, then cancelled. She ended at Pola by October 1918. Her former CO returned, Johann Ulmansky von Vracsevgaj was in post only from 1 September to 31 October 1918. Whe he left she was under control successively of the National Council in Zagreb, the State of Slovenes, Croats and Serbs, still wearing the old Austro-Hungarian flag, but after the the Armistice of Villa Giusti, she was seized by the Italians and thei raised the RM flag in turn on 9 November. She rotted away until attribution was sanctioned in 1920 and BU in Pola.

Read More

The German Submarine War, 1914–1918, R. H. Gibson and Maurice Prendergast
Jiri Novak: Austro-Hungarian Submarines in World War I.
Baumgartner, Lothar; Sieche, Erwin (1999). Die Schiffe der k.(u.)k. Kriegsmarine im Bild
Conway’s all the world’s fighting ships 1906-1921.

Links

https://web.archive.org/web/20170319063128/http://navypedia.org/ships/austrohungary/ah_ss_u1.htm
https://warhistory.org/article/austro-hungarian-submarines
https://en.wikipedia.org/wiki/U-1-class_submarine_%28Austria-Hungary%29
https://www.navweaps.com/Weapons/WTUS_PreWWII.php
https://uboat.net/wwi/boats/index.html?boat=KUK+U1
https://web.archive.org/web/20170319023126/http://navypedia.org/ships/austrohungary/ah_ss.htm