As part of a group of six submarines selected for Mediterranean service, UB-45 was broken into railcar-sized components and shipped to Pola where she was assembled and then launched and commissioned in May 1916.

[6] The German Imperial Navy ordered UB-45 from AG Weser on 31 July 1915 as one of a series of six UB II boats (numbered from UB-42 to UB-47).

[6] The U-boat could carry up to 27 tonnes (27 long tons) of diesel fuel, giving her a range of 6,940 nautical miles (12,850 km; 7,990 mi)at 5 knots (9.3 km/h; 5.8 mph).

Her electric motors and batteries provided a range of 45 nautical miles (83 km; 52 mi)at 4 knots (7.4 km/h; 4.6 mph) while submerged.

[1] As one of six U-boats selected for service in the Mediterranean while under construction, UB-45 was broken into railcar-sized components and shipped overland to the Austro-Hungarian port of Pola.

[12] Two days later, the French ship Ville de Rouen was sunk 120 nautical miles (220 km; 140 mi) southwest of Cape Matapan.

[11] Germany's conquest of Romania provided the German Imperial Navy with sufficient fuel oil for submarines to operate in the Black Sea.

UB-45 and three of her sister ships in the Pola Flotilla were ordered to Constantinople and, en route, had to navigate through the Dardanelles, which had been heavily mined by the Allies in the middle of 1916.

[16] Two days later, the U-boat torpedoed the 3,701 GRT Gioconda, another Russian transport, 45 nautical miles (83 km; 52 mi) off Trebizond.

[11] At 14:30 on 6 November, UB-45 was departing Varna, Bulgaria, under escort by the Bulgarian torpedo boat Strogi that had cleared a path through Russian mines.

[18] In 1932, the Bulgarian Navy conceived a plan to search for the wreck of UB-45 with the intent of raising it for restoration as a training vessel, or, at the very least, to recover the sunken U-boat's 8.8-centimeter (3.5 in) deck gun.

[19][Note 6] UB-45's deck gun was reused, however, and one of the U-boat's diesel engines was restored to operating condition and used on the training ship Assen.