U-45 had sunk a mere two merchant vessels before its career came to an end as a result of its destruction on October 14, 1939 by three British destroyers. U-45 had a maximum speed of 17 knots above water and 8 knots submerged. The craft was powered by two large diesel engines and two electric engines while its operational range was 16,000 kilometers. Its total length was 66 meters while its total displacement was 680 metric tons. The armament of U-45 consisted of five torpedo launch tubes with a single SK C/35 Naval Gun (88mm). Furthermore, the submarine was also equipped with a FlaK 30.