On 10 May 1942 she left Germany for operations in the
Atlantic. Moving by stages down the
English Channel, and after
an engagement with British
coastal forces on the 13th which saw the loss of two torpedo boats (German) and one MTB (British),
Stier reached Royan in occupied France on the 19th. From there she departed under the command of
Fregattenkapitän (later
Kapitän zur See) Horst Gerlach for operations in the South Atlantic. On a cruise of 4½ months she sank three ships. On 27 September 1942, she engaged and sank American cargo ship , whose resistance inflicted so substantial damage that Stier had to be scuttled by her crew. During her operation the
Stier sank four ships, totalling 29,409 tons (GRT).
Final engagement On 27 September 1942
Stier encountered the American
Liberty ship Stephen Hopkins en route from
Cape Town to
Paramaribo. Closing in foggy conditions, the two ships sighted each other around 08:52 AM at a distance of 4,000 yards. Gerlach sent his men to action stations; the master of the
Stephen Hopkins was suspicious of the unidentified vessel and did the same. The
Stephen Hopkins had a small defensive armament (1 × 4 inch gun astern, 2 x 37mm guns of an unknown model forward, and 6 x machine guns), but when firing commenced, around 08:55, she put up a spirited defense. She scored several hits on
Stier, damaging her engines and steering gear. However, overwhelmed by fire from
Stier, the
Hopkins drifted away; by 10 a.m. she had sunk. Forty-two of her crew were killed in the action, and three more died later; the fifteen survivors finally reached
Brazil 31 days later.
Stephen Hopkins's commander, Captain Paul Buck, was posthumously awarded the
Merchant Marine Distinguished Service Medal for his actions. So was
United States Merchant Marine Academy cadet Edwin Joseph O'Hara, who single-handedly fired the last shots from the ship's 4-inch gun. Meanwhile,
Stier had been heavily damaged: unable to make headway, and not responding to the helm. Gerlach made the decision to scuttle the ship and prevent her from falling into Allied hands. After the scuttling charges were exploded,
Stier sank at 11:40 AM. All but two of her crew survived the fight, and returned to France on the German supply ship , which was accompanying
Stier at the time of the action. ==Raiding career==