The United Nations Space Command (UNSC) serves as the military, exploratory and scientific agency of the Unified Earth Government (UEG). It was formed during the Interplanetary War to defeat the communist Koslovic and fascist Frieden forces. It proved highly successful, and later absorbed the United Nations. It has since been the main military of the UEG, fighting the First, Second and Third Insurrections, the Human-Covenant War and the First Apocolyptic War. Eventually during the First Apocolyptic War they were seen as corrupt and destroyed by the Union of Socialist Rebellion. They were later replaced by the United Galactic Alliance.