His appointment to command the 6th Division meant that Mackay led its—and the Australian Army's—first battles of the war. Doubts about Mackay's ability soon disappeared with the commitment of the division to Operation Compass. During the Battle of Bardia, in Libya in January 1941, the 6th Division captured the fortified town along with 36,000 Italian prisoners. For this success, Mackay was made a Knight Commander of the Order of the British Empire (KBE). In a war of rapid movement over long distances, Mackay demonstrated careful planning and recognised the need to reinforce success. He also impressed others with the way he cared for soldiers' lives. "Not only do I want Tobruk quickly", he told his brigadiers before the battle, "but I also want it cheaply". The victory at Bardia was followed by successes at Tobruk, Derna and Benghazi.