U-boats type XXIII were belonged to the new generation of German WWII submarines.
Projects of new types submarines were worked out in Germany from the end of 1942. Designers paid the main attention to increase of speed and range in the submarine position. It was achieved by the increase of accumulator capacity, electro-motors power and new type hull shape. There were provided installation of “Schnorkel” and perfect hydro acoustic apparatus, and was reduced the level of mechanisms and screw noise. To the mid 1943 there were designed projects of «electric subs» – ocean type XXI and little coastal type XXIII.
Submarines type XXIII were built by line-section production. It was planned to build about 1000 units. The final assembling was made in Deutche Werft in Hamburg and Germania Werft in Kiel. The leading submarine U 2321 were delivered June 12, 1944. To the end of the war it were assembled 63 ships.
From February, 1945 six submarines (U 2321, 2322, 2324, 2326, 2329 и 2336) were performed 10 battle cruises and were sunk 4 Allied merchant ships without self losses. May 7, 1945 U 2336 was sunk 2 steamers. They became last German submarine victories in WWII.
After the end of war U 2353 was delivered to USSR and served in Soviet Navy as N-31 to 1953. In 1956 sunken U 2365 и U 2367 were raised and had became first FRG Navy submarines as «Hai» («Shark») and «Hecht» («Pike»).