The Italian submarine Tritone was on the second day of her maiden voyage on January 19, 1943 when she was located by ASDIC on HMCS Port Arthur K-233 near Bougie (Bejaia), Algeria. The Canadian ship was part of the escort for convoy MKS-6 (outbound to the UK). A depth charge attack was made, but the only noticeable result was to knock out her own ASDIC set. Because Port Arthur was now blind to the target her commander, Lt. Commander Edward Theodore Simmons, RCNVR signaled to HMS Antelope H-36, another escort, to come to her assistance and continue the attack.

Antelope moved in and shortly thereafter Tritone surfaced. The boat was sinking by the stern from damage caused by the depth charge attack and the crew were in the process of abandoning, which was clearly seen by the two warships. HMS Antelope fired on the boat with her main guns hitting the target several times, several crewmen were killed while trying to get off the boat, an action criticized later by the Italian crew. The Tritone went down with several men still inside being unable to escape. The twenty-six survivors, including her commanding officer, Capitano di corvetta Paolo Monechi, were picked up by Antelope.