1915 the German Kaiserliche Marine constructed a medium ocean-going submarine, the UB-III class (UB-48 and following).
From spring 1916 some 201 boats were ordered until the end of the war and 157 units were laid on keel.
84 boats made 272 merchant war cruises from summer 1917 to the armistice, 34 got lost in combat.
The UB-III class was the largest single class of submarines in the German navy, representing a quarter of the 332 active German submarines in WWI.
The UB-III submarines sank over 500 allied and neutral merchant ships, with over 1.2 Mio. BRT.
They were based in the German Nort Sea bases Wilhelmshafen, Emden, Bremerhaven, Bruensbuettel, Helgoland, as well as in Bruegge (Flanders) and in Pola and Cattaro (Austrian Adria).
Their operation areas were the Atlantic west of the British Isles, the Channel, the Biscaya and the Mediterranean.
After the Armistice 62 active, half-ready and school-boats were surrendered at Harwich, England.
3 boats (UB-94, UB-99, UB-154) became french, 2 (UB-88, UB-148) US and 2 (UB-125, UB-143) japanese war booty.
The USA and Japan used theit boats for technical studies. The French navy commissioned their units 1920 as Trinite Schillemanns, Carrissan und Jean Corre.
The were stationed in Brest and later Bizerta, North Africa, and served until 1935 in the French navy.
1918 the Kaiserliche Marine had made plans for a modified UB-III boat, the UG-class, but this class was never laid up.
1926 and 1930 the German navy planned to build the UG-boats in case of a war. The UG-plans became the matrix for the new type VII-uboats, which were build from 1935 on.