Here at LSOZI, we take off every Wednesday for a look at the old steam/diesel navies of the 1833-1954 period and will profile a different ship each week. These ships have a life, a tale all their own, which sometimes takes them to the strangest places.- Christopher Eger
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Warship Wednesday, July 16, 2025: Flat Iron Warrior
Above we see the Norwegian Gor-class gunboat-turned-minelayer KNM Tyr, all 102 feet long with a 4.7″/40 EOC gun forward and mines stowed aft. Downright ancient when the Germans came in 1940, she nonetheless proved a serious thorn in their side.
Norwegian Rendels
Starting in the 1870s, the Norwegians embarked on a program of modern warship construction, including steam engines and iron/steel hulls. Constructed locally at Carl JohansVærns Værft, Horten, they ordered eight 2nd class gunboats (Kanonbåt 2. kl) running between 250 and 420 tons, three first class gunboats of between 720 and 1,280 tons, a 1,045-ton steam corvette, an armed 350-ton minelaying “crane vessel” (Kranfartøy), and 14 assorted (45 ton-to-107 ton) 2nd class torpedo boats by 1902. Meanwhile, four 4,000-ton coastal battleships (Panserskibe) with 8.2-inch guns and up to 8 inches of armor would be ordered from Armstrong in the 1890s.
The eight 2nd class gunboats were all of the “flat iron” or Rendel type, a common format introduced by Armstrong in 1867 and built under contract for or copied by over a dozen fleets around the globe, including Norway’s neighbors Denmark and Sweden. Short and stubby, typically about 100 feet long with a 30-foot beam, they were flat-bottomed and drew a fathom or less, even under a full load. This hull form and their anemic compound steam engines only allowed for a speed in the 8-10 knot region, leaving these as defensive vessels ideal for guarding strongpoints and key harbors.
Armament was typically a single large (8-to-15-inch!) gun that could be lowered and elevated inside a shielded battery but not traversed, with the gunboat coming about to aim the horizonal.
The Norwegian Rendels included KNM Vale and Uller (1874, 1876, 250t); Nor, Brage, and Vidar (1897-1882, 270t); Gor and Tyr (1884, 1887, 289-294t); and Æger (1893, 420t). The first five carried a single Armstrong 26.67 cm (10.5-inch) RML forward and two 1-pounder Hotchkiss guns amidships.
Kanonbåt 2 kl Brage’s crew with her Armstrong 26,7cm RML.
Æger toted a more modern 8.3-inch Armstrong breechloader and three small (one 10-pdr and two 4-pdrs).
Æger. This 109-foot 420-tonner was the pinnacle of Rendel development. A one-off design, she was decommissioned in 1932 and her name recycled for a new Sleipner-class destroyer. NSM.000460
Gor and Tyr each carried a single breechloading Krupp 26 cm (10.2 inch) L/30 gun (606-pound shell, 192-pound charge, m/v 1805 ft/secs), the same model gun used on the 3,700-ton Japanese Armstrong-built protected cruisers Naniwa and Takachiho, backed up, like most of the other Norwegian Rendels, by two 1-pounder Hotchkiss guns.
Kanonbåt 2. kl. Gor (b. 1884, Karljohansvern Verft, Horten), note the large Krupp gun forward. NSM.000459
Japanese officers of the protected cruiser Naniwa posing near one of her 26 cm (10.2″) Krupp guns, 1885
Meet Tyr
Constructed as Yard No. 67 at Horten, Tyr was named for the one-handed Norse god of war who sacrificed his other hand to trap the wolf Fenrir. Laid down in 1884, she launched on 16 March 1887 and, fitting out rapidly, joined the Norwegian fleet shortly after.
Norwegian gunboat KNM Tyr from 1887
After 1900, with the looming formal separation from Sweden on the horizon and the prospect of a possible fight on their hands, the Norwegians upped their torpedo boat numbers rapidly to nearly 30 boats as their four new bathtub battleships arrived on hand from Britain. With that, the Rendels transitioned to more static support roles around this time, such as minefield tenders at strategic coastal fortifications and depot ships.
Around this time, most landed their obsolete main gun in exchange for something more contemporary, with most picking up a trainable QF 4.7″/40 Elswick 20-pounder behind a shield. This allowed the removal of their armored bow bulwark. Gor and Tyr also picked up a high-angle 76mm mount, while some of the older boats received a 47mm mount.
Gor as minelegger with mines aft.
After Norway got into the submarine business in 1909 with the small (128-foot, kerosine-engined) German-built KNM Kobben, Tyr became her tender until 1914.
K/B 2 kl Tyr as tender with Norwegian submarine Kobben alongside. MMU.944062
Tyr plan 1913, slick-decked as tender.
With the mine warfare lessons reverberating around the globe after the Russo-Japanese War, it became obvious how easy these broad-beamed shallow-draft craft could be converted to minelayers. This typically meant installing twin port and starboard rail tracks on deck running about 65 feet to the stern for easy planting either via boom over rail drop. On the Gor and Tyr, this allowed for as many as 55 mines stowed on deck.
Tyr as mine planter with her 4″/40 forward and two 37mm 1-pounders on her amidships bridge deck. Model in the Horten Marinemuseet.
Same model, note the mine arrangement. The model omits her 6-pounder 76mm gun.
mines on converted Norwegian 2c gunboat, pre-1940
Same as above
Same as above
1929 Jane’s abbreviated listing of seven of the old Rendel gunboats, including Tyr. Note that Gor is still listed with her old 10-inch Armstrong. The larger Aegir was listed separately and was disposed of in 1932.
War!
September 1939 brought an uneasy time to Scandinavia. The remaining seven Norwegian Rendals, all by this time working as minelayers, bided their time and clocked in on the country’s Nøytralitetsvakt (Neutrality Watch).
Tyr was placed under the command of Orlogskaptein (LCDR) Johan Friederich Andreas Thaulow “Fritz” Ulstrup and stationed at the outer ring Lerøy Fortress overlooking the narrow Lerøyosen south of Bergen. Ulstrup, 43, was a career naval officer who was minted in the Great War and, having studied in France from 1922 to 1924, was serving as an instructor at the Naval Academy in Bergen when the war started.
Ulstrup, who doubled as fortress commander at Lerøy, also had a flotilla of five small armed auxiliary guard boats– Haus (135grt), Lindaas (138grt), Alversund (178grt), Manger (153grt), and Oygar (128grt)– and an old (circa 1898) torpedo boat, Storm, under his control. However, the fort itself, slated in 1939 to receive a 120mm gun battery with four old L/40 French-built Schneider weapons from the decommissioned border forts of Vardasen and Gullbekkasen pointing toward Sweden, instead only had a couple of 65mm Cockerill guns and searchlights.
On the early morning of 9 April 1940, just after midnight, two cruisers appeared off Bergen and flashed that they were the RN’s HMS Cairo and Calcutta, when in fact they were the German Kriegmarine’s light cruiser sisters Koln and Konigsberg, each with nine 15 cm SK C/25 (5.9-inch) guns, as the Gruppe 3 invasion force under RADM Hubert Schmundt. The cruisers were followed by 600 troops of the Wehrmacht’s 69th Infantry Division on the 1,800-ton gunnery training ship (Artillerieschulschiff) Bremse with four 12.8 cm SK C/34s, the torpedo boats Wolf and Leopard, and the E-boat tender Carl Peters shepherding S19, S21, S22, S23, S24, and naval trawlers Schiff 9 and Schiff 18.
Tyr, loaded with live and armed mines picked up at Laksevåg, was at the ocean-front fishing village of Klokkarvik, directly in the path of the Germans.
Klokkarvik harbor during the neutrality watch in 1939/40. In the picture, you can see a mine-armed KNM Tyr at anchor with a Draug-class destroyer at the quay. Note the Royal Norwegian Navy’s Hover M.F.11 floatplane in the foreground. (Source: Naval Museum Horten)
When the Germans began to creep into the fjord and with word of other sets of foreign warships in the Oslofjord, Ulstrup, who had been arguing with Bergan’s overall commander, RADM Carsten Tank-Nielsen all day on the 8th to be able to sow his mines, finally obtained clearance at 0030 for Tyr to hurriedly drop eight mines between Sotra and Lerøy, closing Lerøyosen. However, the 10-14-hour time-delay safety features on the magnetic contacts of the mines meant they were still dormant when the German cruisers passed harmlessly over them. Storm, meanwhile, fired a torpedo at Carl Peters at 0220 but missed.
Ulstrup closed to shore so he could place a quick phone call to Tank-Nielsen to apprise him of the situation, then returned to his minelayer to beat feet toward Bjørnefjord, playing a cat and mouse game with German E-boats and reportedly landing a hit from her 4.7-inch gun on one, receiving several 20mm hits from the Schnellbooten in exchange.
Further up the fjord, batteries at the now-alerted Norwegian inner ring Forts Kvarven (3 x 210mm St. Chamond M.98s) and Sandviken (3 x 240mm St. Chamond L/13s) opened up on the passing Germans at 0358 and soon landed hits on both Konigsberg and Bremse in the darkness of pre-dawn, leaving the former adrift with flooded boiler rooms. While Tyr, Ulstrup, and company managed to withdraw further into the fjords– laying another 16 mines in the Vatlestraumen approaches north of Bergen– Bergen itself fell to the German seaborne force just hours later.
However, the crippled Konigsberg would be hammered by a strike of RNAS Sea Skuas out of Orkney once the sun came up and caught five 500-pound bombs, sinking her in the harbor on 10 April.
Meanwhile, Tyr’s mines near Vatlestraumen sank the packed German HSDG freighter Sao Paulo (4977grt) on the evening of the 9th, sending her to the bottom in 260 feet of water.
The 361-foot Hamburg-Südamerikanische Dampschiffahrts-Gesellschaft steamer Sao Paulo was lost to one of Tyr’s mines.
In trying to sweep the mines, the German naval auxiliary Schiff 9 (trawler Koblenz, 437grt), and the auxiliary patrol boat Vp.105 (trawler Cremon, 268grt), along with two launches from Carl Peters, were lost on the 11th. Some sources also credit the German steamer Johann Wessels (4601grt), damaged on 5 May, and the German-controlled Danish steamer Gerda (1151grt), sunk on 8 May, as falling to Tyr’s eggs.
Withdrawing down the 114-mile-long Hardangerfjord, Ulstrup was appointed the commander of this new sector on 17 April and, moving ashore to Uskedal, left Tyr to her XO, the 47-year-old Fenrik (ensign) Karl Sandnes. Ulstrup, stripping the 37mm guns from Tyr and two 65mm guns from auxiliary gunboats, mounted them on flatbed trucks as improvised mobile artillery.
A 1937 Chevy flatbed with a 65mm L35 Hotchkiss under Ulstrup’s dirt sailors, April 1940
The next two days saw a series of skirmishes around Uskedal, in which Tyr closed to shore to use her 4.7-inch gun against German positions in improvised NGFS, coming close enough to get riddled by German 8mm rifle fire in return.
A naval clash on the 20th involving the advancing Germans in the Hardangerfjord saw Tyr, under the command of Sandnes, shell the German auxiliary Schiff 18, which beached at Uskedal to avoid sinking. The same battle saw the Norwegian Trygg-class torpedo boat Stegg sunk by Schiff 221 while the Norwegian armed auxiliary Smart was sunk by Bremse. The German minesweeper M.1 went on to capture five Norwegian-flagged steamers that were hiding in the fjord.
With Ulstrup and his force ashore getting ready to displace inland under fire, and Tyr trapped in the fjord, Sandnes brought his command to the shallows and, attempting to camouflage her, hid the breechblock for her 4.7 and evacuated the old minelayer. By forced march, they made it to Matre, some 14 miles on the other side of the mountain, and soon rejoined Allied lines.
Meanwhile, Tyr was soon discovered by the Germans, who towed her back to Bergen and, along with her fellow Rendel gunboat-turned-minelayer cousin, Uller, were soon pressed into service with the Kriegsmarine.
On 30 April, Tyr and Uller left occupied Bergen with German crews on a mission to mine the entrance to Sognefjord, barring it to British ships. This service would be short-lived as a Royal Norwegian Navy Heinkel He 115 seaplane spotted the pair, now under new management, and bombed Uller seriously enough to have her crew beach on a reef and evacuate on Tyr. Uller later lifted off the reef and sank near Gulen, becoming a popular dive spot.
As for Tyr, she saw no further direct combat, although the Germans likely continued to use her in some form of coastal service for the rest of the war.
Post-war
Tyr was still afloat in 1945 when the Germans were run out, and was subsequently sold on the commercial market. Her old hull still in good shape, she was converted to an economical diesel plant and sailed for a time as a heavy lift steamship.
By 1951, she had been converted to the car ferry Bjorn West, a task she fulfilled for three decades. Further converted for service in a salmon farming operation.
Found in poor condition ten years ago, she recently passed to a consortium of Vestfold county municipality, the KNM Narvik Foundation in Horten, and the Bredalsholmen Shipyard and Preservation Centre, who, with Tyr safely in drydock in Kristiansand, plan on restoring her to her 1940 condition. At this point, she is believed to be the last Rendel-type gunboat.
They plan to make her sailable, which isn’t that far-fetched.
Epilogue
The Norwegian Navy has recycled our gunboat/minelayer’s name at least twice.
The first was an Auk-class minesweeper, ex-USS Sustain (AM-119), which was transferred in 1959 and served as KNM Tyr (N47). Three Auk-class sisters transferred with her (ex-USS Strive, Triumph, and Seer) were named Gor, Brage, and Uller, in a nod to the old Rendel boats that saw WWII service.
Ex-USS Sustain (AM-119) as KNM Tyr (N47). Commissioned 9 November 1942, she earned eight battle stars for her World War II service from North Africa to France to Okinawa, helping to sink at least one U-boat in the process. She served the Norwegians from 1959 to 1984.
The third KNM Tyr in Norwegian service, N50, was bought commercially in 1995 and spent two decades mapping and filming dozens of historic wrecks in the country’s waters with her ROVs, including Scharnhorst and HMS Hunter (H35).
The intrepid LCDR Ulstrup continued to resist the Germans after leaving Tyr in April 1940. He crafted a makeshift shoreside torpedo battery, the only torpedo available being salvaged from the wreck of an old torpedo boat, and managed to caravan mines from a storage facility in Sogn to Ulvik to surprise the occupation forces. Once the Allies pulled out in mid-June, he was left to his own devices with a resistance group that became known, logically, as the Ulstrup Organisasjon.
With the heat getting too close for comfort, Ulstrup and a dozen other patriots crowded on the sailing trawler MK Måken (M 366 B) on 19 September 1940 and set out from Alesund for the Shetlands, arriving at Baltasound 11 days later. Welcomed as a hero in London, he was soon in command of the old four-piper HMS Mansfield (G76) (former USS Evans, DD-78), which in April 1941 carried commandos for a raid on Oksfjord, Norway, where the herring oil factory was destroyed.
“HNMS Mansfield, Norwegian Town-class destroyer. She is an ex-U.S. destroyer (USS Evans) and is manned entirely by the Norwegian Navy.” Circa 1941. Note her Norwegian flag. Photo by Harold William John Tomlin, IWM A2725
Once Mansfield was passed on to the Canadians in March 1942 after the Norwegians rode shotgun on 17 Atlantic, Ulstrup, promoted to Kommandørkaptein, was given command of the 11th Department in the Ministry of Defense in London, then subsequently placed in command of the Norwegian forces in Iceland, where he spent the rest of the war.
Returning to Norway with a War Cross with Swords, Ulstrup was promoted to rear admiral in August 1952. After escorting Ethiopian Emperor Haile Selassie on his tour of Norwegian naval bases, including the Horten shipyards in November 1954, he was made a Grand Officer of the Order of the Ethiopian Emperor Menelik II, rounding out his international awards.
Kontradmiral Johan Fredrik Andreas Thaulow Ulstrup, retired, passed in 1956, age 60, having wrapped up a 41-year career.
Tyr’s best-known “kill” of the war, the HSDG steamer Sao Paulo, packed with German military vehicles and stores that never made it to shore, is a favorite of wreck divers.
Meanwhile, in Klokkarvik, a memorial, complete with a mine and a seagull, was dedicated in 2021.
As noted in the town:
The seagull that takes off from the mine is a symbol of optimism. We should be aware of what war brings, but be most concerned with how we can secure peace. We should learn from history, – because it tends to repeat itself. The seagull draws our attention to the sea, the source of everything, our future.
Meminisse est ad Vivificandum – To Remember is to Keep Alive
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