When the Kingdom of Elysia was first founded, the defensive duties in the Kingdom were assigned to the Department of War. Led by Lord Talyn Xam, the Department of War was organised into several divisions based upon the "schools of thought" taught by the Cereans. Individuals were assigned to a division based upon their strongest military talent where they could master their talents before utilizing them on the battlefield. At this time, the Department of War was still in it's infancy and experimentation in the Department's organisation was necessary to maximize it's efficent. The Department of War was brought in to assist with the Bhuna Sound VI project, assisting with the material haulage and acting as consultants for the development of defensive structures. Ultimately, under the orders of Lord Chancellor Revan Jones, the Department of War was reorganized into the Department of Defense and the division structure was scrapped.
Kam Virai, then a Legionary, was appointed as the Department of Defense's Executive Officer and brought in the Battlegroup structure. A Battlegroup consisting of Naval, Marine, Army and Starfighter elements that would allow each Battlegroup to perform a multi-role purpose. The first battlegroup, Battlegroup I, was formed. Shortly after, Kam Virai was appointed as Lord of the Department of Defense as Talyn Xam retired from active duty.
The Department of Defense started it's first operation under Lord Kam Virai: Operation Closed Skies. Under the direction of the Department of Defense, Battlegroup I began the construction and management of planetary shield generators within Elysian territory. During this operation, with the Department overflowing with personnel, a second battlegroup was formed: Battlegroup II.
On Y16D200, Kam Virai resigned his commission citing personal reasons and Praetorian Alik Khan was promoted to Lord of the Department of Defense. To this day, Lord Alik Khan remains in command.