On 6 April 1944, U-302 fired torpedoes at convoy SC-156 and sank Ruth I and South America, but was herself lost after the attack.

The South America (Master Alf Ambjørnsen) was hit on the port side by a torpedo between the #3 wing tank and #8 center tank behind the pumproom and caught fire immediately. Five minutes later, a second torpedo struck aft, resulting in an enormous explosion that apparently extinguished the fire, but the tanker broke in two and settled in the middle. The men on the poop abandoned ship in a raft and a lifeboat and seven men from amidships abandoned ship in the starboard lifeboat. All were picked up after a short time by the British rescue ship Goodwin, which then went to rescue survivors from the Ruth I, but they were already picked up by another vessel. About 45 minutes later, the rescue ship returned to the tanker, only to find both parts of the ship high in the air with the amidships section below water. The following day, an escort was sent to the wreck to recover the papers of the ship and confidential books, but in the meantime the stern had sunk and only the bow was still visible. All survivors were landed in Gourock on 13 April.