Type XXIII U-boats were designed to operate in the shallows of the North Sea, Black Sea and Mediterranean Sea where larger Type XXI Elektro boats were at risk in World War II. They were so small they could carry only two torpedoes, which had to be loaded externally.

The first Type XXIII, U-2321 , was launched from Deutsche Werft in Hamburg on April 17, 1944. It was one of six XXIIIs that went on operational patrol around the British Isles in early 1945. Forty-eight others followed from Deutsche Werft and 13 from Germaniawerft of Kiel. U-4712 was the last one launched, on April 19, 1945.

The first patrol of a Type XXIII began late in the war when U-2324 put to sea on January 29, 1945. U-2336 under the command of Kapitänleutnant Klusmeier sank the last ships lost in the war, on May 7, when he torpedoed two British freighters inside the Firth of Forth.

None of the six operational Type XXIIIs -- U-2321 , U-2322 , U-2324 , U-2326 , U-2329 and U-2336 -- were sunk by the Allies but they sank or damaged five ships for a total of 14,601 tons.

Seven Type XXIIIs were lost to various causes.

• U-2323 was sunk by a naval mine on July 26, 1944.
• U-2331 was lost in a training accident on October 10, 1944.
• U-2338 was the only XXIII to be sunk by the enemy. British Beaufighter aircraft killed 12 crewmen and sank the boat east-northeast of Frederika on May 4, 1945, before she ever went on combat patrol.
• U-2342 was sunk by a naval mine on December 26, 1944.
• U-2344 was rammed and sunk by U-2336 on February 18, 1945.
• U-2351 was paid off in April 1945 after bomb damage.
• U-2367 was rammed and sunk by an unidentified U-boat on May 5, 1945.

In early May 1945, 31 XXIIIs were scuttled by their crews. Twenty surrendered to the Allies and were sunk in Operation Deadlight. Only three -- U-2326 (later British submarine N-35 ), U-2353 (later British submarine N-37 ), and U-4706 (later Norwegian submarine Knerten ) -- survived the war.

U-2321 - U-2322 - U-2323 - U-2324 - U-2325 - U-2326 - U-2327 - U-2328 - U-2329 - U-2330 - U-2331 - U-2332 - U-2333 - U-2334 - U-2335 - U-2336 - U-2337 - U-2338 - U-2339 - U-2340 - U-2341 - U-2342 - U-2343 - U-2344 - U-2345 - U-2346 - U-2347 - U-2348 - U-2349 - U-2350 - U-2351 - U-2352 - U-2353 - U-2354 - U-2355 - U-2356 - U-2357 - U-2358 - U-2359 - U-2360 - U-2361 - U-2362 - U-2363 - U-2364 - U-2365 - U-2366 - U-2367 - U-2368 - U-2369 - U-2371 - U-4701 - U-4702 - U-4703 - U-4704 - U-4705 - U-4706 - U-4707 - U-4709 - U-4710 - U-4711 - U-4712

General Characteristics

• Displacement: 234 tons surfaced, 258 submerged, 275 total
• Length: 34.7 m overall, 26 m pressure hull
• Beam: 3 m
• Draught: 3.67 m
• Height: 7.7 m
• Power: 630 horsepower (470 kW) surfaced, 580 horsepower (433 kW) submerged
• Speed: 9.7 knots (18 km/h)surfaced, 12.5 knots (23 km/h) submerged
• Range: 2600 nautical miles (4,800 km) at 8 knots (15 km/h) surfaced, 194 miles (359 km) at 4 knots (7 km/h) submerged
• Torpedoes: two bow tubes
• Complement: 14-18 men
• Maximum depth: 180 m