Assigned to operate as part of the Otranto Barrage in the Strait of Otranto between Brindisi, Italy, and Corfu, S.C. 94 arrived at Corfu on 5 June 1918 as part of a convoy consisting of 21 submarine chasers and their mother ship, the former collier and survey ship USS Leonidas.

[2] On the evening of 18 June 1918, Unit F was on an antisubmarine patrol in the Strait of Otranto when it became involved in a friendly fire incident.

The submarine chasers challenged the British destroyers with recognition signals flashed several times by blinker light.

Defender and Nymphe immediately flashed lights at the submarine chasers, which ceased fire, went alongside the destroyers, and discovered their identities.

Discussing the incident in a letter to the British Admiralty, the commander of United States Naval Forces Operating in European Waters, Vice Admiral William Sims, wrote: "While it appears that, under attendant circumstances, the commanding officers of the submarine chasers were justified in opening fire on the destroyers, I nevertheless wish to express regret that the incident occurred, and that H.M.S.