Type XXIII(23) was one of World War II’s most modern submarines. It was a real submarine in the sense that it could stay submerged for a long time and cruise at high speed under water.

With a weight of approximately 275 tons and a crew of only 12 men the Type XXIII was one of the smallest submarines which were produced in the German shipyards during the World War II.

The production was done at three different shipyards which each created a module to the submarine. They were sailed to the German coast on the German rivers and welded together. The idea was that if a single shipyard was bombed the others could take over and thus keep the war machine running.

Small but dangerous
Through it’s hydrodynamic shape and the electrical machinery the Type XXIII was created to cruise faster under water than above. It could maintain a speed of 12.5 knots under water, but only 9.7 knots on the surface. That was a special ability during the World War II since most submarines was primarily designed to stay on the surface and only dive when they had to sneak up on a ship or if they were under attack from aircrafts etc.

The larger submarines had a massive superstructure with several guns and a high tower which gave a lot of drag under water which resulted in a low top speed. Typically as low as 7-8 knots. Added to this the big batteries was quickly drained of power when a large submarine like U-534 on 1500 tons would be driven by electric motors under water.

The short range and low speed in submerged condition also meant that they could easily be taken by surprise by the long-range aircraft, the B-24 Liberator, which was developed by Americans in response to the very serious threat from Hitler’s submarines in the Atlantic.

Submarines were often merged to recharge their batteries or cruising to reach the hunting areas. If they were attacked at an unfortunate time they either couldn’t dive due to lack of electrical power or the slow speed under water made it easy for the pilots to figure out where to drop their depth charges.

The Type XXIII didn’t have those problems. Armed with only two torpedoes and with a length of 35 meters it wasn’t designed for long voyages in the Atlantic but for war in coastal areas. It could submerge very quickly during a panicdive – as fast as 9 seconds. The large submarines used up to one minute on the same maneuver. Sometimes that wasn’t fast enough.

The compact design also meant that a Type XXIII had to reload torpedoes by tipping the bow out of the water and put them in with a crane from the outside.

The small submarines never got to play a crucial role in the war. Only six were engaged in combat patrols starting in January 1945. All together they sank four allied ships. The remaining of the 61 build Type XXIII were all on training missions, typically in the Baltic Sea or in some other stage of making ready for war.

Aftermath for the Type XXIII
32 submarines of the Type XXIII ended up being sunk by their own crew when the leader of the German Kriegsmarine, Admiral Dönitz, on April 31, 1945 issued orders to launch “Operation Regenbogen”.

The submarines were under no circumstances to fall into enemy hands and therefore they had to be sunk and mined. The plan was to recover them later when the luck of war turned in favor of the Nazis again. That never happened. Only a single Type XXIII was raised after the war and put into service of the somewhat amputated German naval. Unfortunately it sank – again – during an exercise at “Dokker Banke” and this time it took the entire crew into the depths of the North Sea.

Many of the other submarines that were sunk in Denmark during Operation Regenbogen was in the post-war salvaged by fishermen who suddenly were able to make a living by salvaging scraps from sunken warships.

This happened to U-2338 which was sunken off Fredericia in an attack by British aircrafts. The same attack which the only remaining Type XXIII, U-2359, barely escaped from. Other wrecks were just blown away if they posed a threat to naval traffic.

20 other of Type XXIII was surrendered to the allies after Germany’s capitulation and subsequently used in Operation Dead Light. One of them was the U-2359′s “wingman” U-2334 which escaped the British Mosquito during the attack on May 2nd. U-2334 reached it’s destination in Kristiansund, Norway, but here the captain surrendered the ship immediately to the Allied forces that were waiting on the quayside.

What happened then, to the modern submarines of valuable steel, may seem a bit special today. “Operation Dead Light’s” main purpose was getting rid of all unwanted German submarines because they gave associations to bad memories and because no one wanted them to be used again. Therefore they were used as targets for warships and aircrafts during shooting exercises.

A total of 121 submarines were sunk in deep waters off Ireland during Operation Dead Light.

This was long before the submarines had any historical value.

The only Type XXIII that anyone knows of is the U-2359 that was located by Ternen off Laessoe in 2007.