Operation: MACARTHUR was a joint United Nations Space Command and Sangheili Armed Forces strategic offensive against the Blood Covenant during the War of Vengeance from 2556 to 2558 in order to weaken the Blood Covenant's infrastructure and defensive capability in preparation for another great offensive in the same manner of Operation: TACK HAMMER. In conjunction with the UNSC's campaign of Unrestricted Prowler Warfare, this resulted in severe damage to the Blood Covenant's infrastructure and military-industrial complex, allowing the alliance to strike the final series of killing blows in Operation: FURY in 2560.