At 18.04 hours on 22 June 1940 U-65 reported the sinking of an unescorted tanker of 7000 grt with a spread of two G7e torpedoes about 70 miles southwest of Penmarch in the Bay of Biscay. The ship was immediately covered in burning oil and apparently broke in two before it sank.

On 17 June the Monique had been re-routed to Brest and then to Belle-Ile due to the German advances, but was reported missing after being last seen by the French motor tanker Rhéa in the evening of 17 June. A radio message indicated that the ship had been attacked by aircraft off Verdon on 21 June, but it is more likely that she was sunk by this U-boat attack one day later because HMS Broke (D 83) (Cdr B.G. Scurfield, RN) reported that she scuttled a wreck identified as Monique in position 46°45N, 06°10W in the late evening of 22 June. The bodies of two of her sailors later washed ashore near La Coruña, Spain.