A new convoy, codenamed Operation Excess was on its way through Malta with ammunition supplies. "Excess" coincided with the arrival of the "Luftwaffe" "Fliegerkorps" X (10th Air Corps) in Sicily to support the faltering Italians in the theatre, after the failed invasion of Egypt. On 9 January the "Regia Aeronautica" flew a fighter sweep over the Grand Harbour. Eighteen Macchi C.200s from "6° Gruppo" were engaged in aerial combat. MacLachlan climbed to 22,000 feet and spotted the enemy fighters 10,000 below. He attacked a group of six and shot one down into the sea where it left a large plume of water. MacLachlan circled the sea and noticed the Italian pilot had escaped his aircraft and survived. "Capitano" Luigi Armanino was taken aboard a rescue craft to a prisoner of war camp in Malta, wounded in the thigh and arm. MacLachlan claimed a second Macchi shot down minutes later. The following day he attacked an Italian Fiat CR.42 over the "Excess" convoy as the Italians attacked the ships once more. Four others appeared and they climbed over him and dropped onto his tail. Not risking a five to one encounter, MacLachlan flew over the "Excess" convoy hoping the ship's fire would protect him The British vessels fired at him in error but his aircraft was not hit.