From Naval Staff monograph – ‘The Incident at Cape Lukka’

The despatch of submarines B6 and B11 to the Egyptian coast gave rise to an unfortunate incident. On 16 August , ten miles South of Cape Lukka, a party of Arabs under officers in European uniform was observed displaying a flag of truce. The submarines had anchored at 8 am 700 yards from the shore, and Lt Holbrook, of B11, pulled toward the shore in a Berthon boat to investigate, and spoke from the boat to a person wearing European uniform , attended by a native with a white flag. The circumstances aroused his suspicions, and he began to return to the submarine, when fire was opened from the beach, one of the boat’s crew being killed. and Lt Holbrook and two men wounded. The explanation furnished by the Shaikh of the Senussi was that the submarines were thought to be Italian, for the Arabs were hostile to the Italians. It seems Admiral Peirse was under a misconception regarding the boundary of Egypt.