At 02.36 hours on 14 July 1943 the unescorted Robert Bacon (Master Clyde Frank Henderson) was hit by a torpedo from U-178 about 35 miles off the Mozambique Light. A first torpedo was seen to cross the bow, but a second struck the port side at the #2 hatch in one of the fuel bunkers. The explosion threw oil and water into the air, destroyed steam lines and caused a 10° list to starboard. The engines were secured and the nine officers, 35 crewmen and 27 armed guards (the ship was armed with two 3in and eight 20mm guns) abandoned ship in three lifeboats and three rafts, because two other lifeboats filled with oil and water were unusable.
At 03.14 hours, a first coup de grâce hit the starboard side but she remained afloat. She sank by the bow ten minutes after being hit on the starboard side aft by a second coup de grâce at 04.43 hours. The U-boat surfaced and questioned the survivors in one of the boats, giving them the direction to land and wished good luck before leaving.

This boat set sail and reached on 16 July the Mozambique harbour, where a tug took them in tow to the pier. 14 survivors in a second boat were picked up by the British steam merchant English Prince on 26 July and landed at Beira. The seven men in the last boat were rescued by the British steam tanker Steaua Romana on 27 July in 14°32S/41°11E and landed at Durban. All rafts reached land, the first after 14, another after 20 and the last 44 days after the sinking. Two crewmen and two armed guards were lost with the ship and another crewman died ashore from exposure.