On 13 June "Plunkett" was involved in a 'friendly fire' incident; she attacked the British cable laying ship (1890)HMTS Monarch (1916)|HMTS "Monarch" and its Canadian escort, the Canadian corvette , killing "Monarch"s first mate and a seaman and wounding most of the bridge personnel. More that thirty were wounded, including the ship's Master. "Trentonian", though fired upon, was not hit and rescued survivors in the water and treated wounded. "Monarch" was severely damaged and the cable was cut and lost disrupting installation of critical communications cables to Normandy.