First patrol

U-168's first patrol commenced with her departure from Kiel on 3 March 1943. Her route took her through the Kattegat and Skaggerak, along the coast of Norway, through the 'gap' between Iceland and the Faroe Islands and into the Atlantic Ocean south and southwest of Greenland. She arrived at Lorient in occupied France on 18 May.

Second patrol

The boat then moved into the Indian Ocean, sinking the British steam merchant ship SS Haiching 80 nautical miles (150 km; 92 mi) west southwest of Bombay (now Mumbai), on 2 October 1943.^[4]

She was unsuccessfully attacked by a Catalina flying boat of No. 413 Squadron RCAF on 3 November. Four 250 lb depth charges were dropped.

The patrol terminated in Penang, Malaya (now Malaysia) on 11 November.

Third patrol

The submarine began her third and what would turn out to be her most successful patrol when she departed Penang on 7 February 1944. She fired three torpedoes at the British salvage vessel HMS Salviking south of Ceylon (now Sri Lanka) on the 14th. One of the projectiles malfunctioned, but the other two were sufficiently destructive to send the ship to the bottom.

The following day she sank a Greek ship, Epaminondas C. Embiricos about 130 nautical miles (240 km; 150 mi) north of Addu Atoll in the Maldives. The Master and the Chief Engineer were both taken prisoner and handed over to the Japanese. The former's captivity prevented disciplinary action being taken over why he had ordered the undamaged ship to be abandoned and why the vessel was stationary for two hours, despite standing orders to the contrary.

U-168 also damaged the Norwegian Fenris with her last torpedo on the 21st west of the Maldives, but had no ammunition left for her deck gun to finish the ship off which continued to Bombay under her own power.^[5]

The boat returned to Batavia (now Jakarta) on 24 March.

Fourth patrol and loss

The submarine left Batavia on 5 October 1944. According to normal procedures to safeguard friendly submarines the U-168 gave local Japanese units its precise departure and arrival times, intended course and speed. This was subsequently decrypted and included in a FRUMEL report on 5 October 1944. With little time, the Free Dutch Forces submarine HNLMS Zwaardvisch, under the command of Lieutenant Commander H Goosens, was ordered to intercept. Shortly after sunrise on 6 October, while in the Java Sea, U-168 was spotted on steady easterly course and fired upon by a spread of six torpedoes.^[6][7] The torpedoes were spotted mere seconds before impact, being struck by two. One hit the U-168's pressure hull but failed to detonate. The second hit the forward torpedo room and exploded. Attempts to stem the flooding failed and the U-168 sank rapidly.^[8] The attack killed 23 men, with a further 27 being captured including Pich.^[1] In his interrogation, unaware of Allied code-breaking and signals intelligence, Pich could not explain why he'd been caught unaware with one of his crewmen blaming the Japanese, complaining that they never started anti-submarine air searches before 11:00.^[8] Pich later informed the Dutch commander that his submarine was hit three times though only one torpedo exploded.^[6][7]

U-168 is not believed to have made any defensive maneuvers in the action, thus it is likely that the Germans were sunk without realizing they were under attack until the torpedoes hit. The Kriegsmarine was convinced that the sinking of U-168 was the result of "loose talk" due to the crew who brought their Indonesian girlfriends aboard for a goodbye party. They also assumed that the exact position of U-168 was discovered by the Allies long before the engagement, though Dutch reports suggest that they encountered the Germans simply by chance.^[6][7]

In late-2013 divers found what is believed the wreck of the boat^[9] though it is pointed out that alternatively it could be the wreck of U-183.^[10][11]