From the beginning of World War I, Austria-Hungary had been working to increase the size of its U-boat fleet, so the Imperial German Navy, which was finding it difficult to obtain trained submarine crews, sold two of its UB II boats, UB-43 and UB-47, to its ally in June 1917.

After protracted negotiations, which had stalled over the outflow of Austro-Hungarian gold reserves to Germany, an agreement to purchase two submarines—UB-43 and UB-47—was reached in June 1917.

Each group had slight variations in design, resulting in differences in displacements, lengths, speeds, fuel capacities, and operational ranges.

[1] The two U-43-class U-boats were nearly identical to the eight boats of the Austro-Hungarian Navy's U-27 class, which were built to UB II plans.

[13][14] This group was selected by the German Admiralstab for deployment to the Mediterranean, but, unlike the smaller UB I boats, they could not as easily be transported overland by rail.

[14] UB-43 was ordered by the Imperial German Navy on 31 July 1915 and was laid down by AG Weser of Bremen on 3 September.

[4] UB-43 was broken into railcar-sized components and shipped overland to the Austro-Hungarian port of Pola where Weser workers assembled her.

[19] UB-47 was ordered by the Imperial German Navy on 31 July 1915 and was laid down at Bremen by AG Weser on 4 September.

[14] As one of six U-boats selected for service in the Mediterranean while under construction, she was broken into railcar-sized components and shipped overland to the Austro-Hungarian port of Pola.

[14] SM UB-47 was commissioned into the Imperial German Navy on 4 July 1916 under the command of Oberleutnant zur See Wolfgang Steinbauer.

[14] Steinbauer and UB-47 sank 15 ships (62,676 GRT and 11,100 tons) over the next nine months, including two Cunard Line steamers—Franconia and Ivernia—serving as British troopships, as well as the French battleship Gaulois.

[21] U-47's success under Austro-Hungarian command was less than that under the German flag; only three ships (6,201 GRT and 351 tons) were sunk through the end of the war.