Though the UNSC was initially extremely reluctant to engage in any military operations on a significant scale since the Reconstruction period began, the attack on Unmoving Virtue was the exception to this rule, and the official beginning of the War of Vengeance. Codenamed "Operation: TACK HAMMER" and conducted with the cooperation of the Sangheili Armed Forces Second Fleet of Benevolent Enlightenment, the battle was a significant victory for both participants, and saw the deployment of numerous new technologies. In this regard, it served as a combat test for UNSC prototypes, proving their reliability and effectiveness in the field, and also functioned as a psychological deterrent against further Covenant aggression. For the Sangheili, it saw the liberation of thousands of captured Sangheil