At 07.14 hours on 7 July 1940 the unescorted and unarmed Lucrecia (Master Cornelis Smit) was hit on the starboard side underneath the bridge by one G7e torpedo from U-34 about 70 miles west of the Isles of Scilly. The explosion broke the back of the ship, ignited a fuel tank ahead of the bridge and killed the master who was probably asleep in his cabin. The crew immediately abandoned ship in one lifeboat and some rafts, while the burning tanker settled slowly and sagged in the middle. The column of smoke attracted a patrol aircraft from St. Eval which was shortly thereafter joined by two Sunderland flying boats and the nearby HMCS Restigouche (H 00) (Cdr H.N. Lay, RCN) was ordered to investigate. In the meantime, the submerged U-boat remained in the vicinity in order to wait for the wreck to sink. At 15.20 hours, the Germans spotted another ship near the attack position but could not get closer due to the aircraft and eventually left the area. They had observed how the Portuguese steam merchant Alferrarede picked up the survivors and then proceeded on her voyage to Oporto, where eight officers and 22 crewmen were landed on 11 July. The chief officer had died of his wounds on 8 July and was buried at sea the next day.

Lucrecia broke in two after being torpedoed.

Shortly thereafter, HMCS Restigouche found the abandoned Lucrecia and reported that she could possibly be salvaged because the fire was no longer burning, so the rescue tugs HMS Salvonia (W 43) and HMS Zwarte Zee (W 163) were sent from Falmouth to her position. However, the tanker probably foundered during the night as the tugs were unable to find the wreck the next day.