The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines plus two MWM RS34.5S six-cylinder four-stroke diesel engines for cruising, producing a total of 9,000 metric horsepower (6,620 kW; 8,880 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged.

[4] Under Lüth's command she sailed on two long combat patrols in late 1942 and 1943, patrolling the waters off South Africa and Mozambique and sinking 22 ships for a total of 103,712 GRT,[2] earning him a promotion to Korvettenkapitän and the Knight's Cross of the Iron Cross with Oak Leaves, Swords and Diamonds.

U-181 sailed from her base in Bordeaux, France to Penang, Malaya (now Malaysia) in mid–1944, sinking four ships totalling 24,869 GRT.

[6]: 215  The trip home was aborted when the main bearings started to wear out, prompting a return to Batavia on 6 January 1945, but transferring their fuel to U-843 near the Cocos Islands on the way.

On 6 May, Otto Giese dropped the two code-key machines into the Singapore harbor, and later that day, the boat was "taken" by the Japanese Captain Marujama.

Admiral Paul Wenneker sent the message on 8 May, that Lubeck was in place, "an early agreement between Germany and Japan, if one nation lost and the other continued fighting, the former would render its war material to the latter."