Antares was originally built for AG Bremen but was taken over by the Kriegsmarine when World War II started.

At the beginning of April 1940, Antares was in Szczecin where it loaded coal, horses, soldiers, armored vehicles, trucks, weapons, ammunition, motorcycles, and various supplies that were to go to Norway. Like Amasis, it was to head to Oslo in the convoy Seetransportstaffel 1.

On April 7, 1940, they left Stettin and headed north. To avoid enemy ships, the convoy traveled close to the Swedish coast. The British submarine HMS Sunfish had, after receiving information that German ships were heading north, been lying in wait at Måseskär and at around 5:30 PM on April 10, 1940, sank Amasis with a torpedo, and around 8 PM, they heard the propeller sounds of Antares on board Sunfish, shortly thereafter the submarine fired two torpedoes at Antares, one of which hit in the engine room.

The ship began to sink and those on board tried to get into the lifeboats, but due to the panic situation, several lifeboats capsized and many jumped overboard.

The German minesweepers M-1303 and M-1304, along with the Swedish ship Skagerack, which had been nearby, came to the rescue and they picked up survivors while the Germans attacked Sunfish with depth charges.

From Öckerö, local residents had seen when the torpedo hit its target and the heavy cannonade that followed against the submarine and how Antares quickly sank.

From Käringön, the rescue and pilot boats went out to save survivors, but due to the gunfire, which continued with unabated strength until around 9 PM, they did not dare to go out too far.

From Lysekil, a convoy of 8-10 transport ships was observed moving quickly north along the Swedish coast with destroyers and aircraft. When Antares sent out a distress signal at around 8 PM and reported that it had been torpedoed, rescue boats also departed from Lysekil.

Around 9 PM, the gunfire ceased and the rescue boats made their way to the wreck site where a number of bodies floated in the water. Searchlights from the ships searched for several hours, but only 34 people could be rescued and after questioning these, it emerged that about 200 people had been on board when the ship sank.

Germany thanked Sweden for the assistance with the crews from Amasis and Antares.