Foss was an admiral in the Imperial Academy during the reign of the Galactic Empire. Emperor Palpatine informed Captain Voss Parck that Imperial cadet Eli Vanto and the Chiss Thrawn were to be admitted into the Royal Imperial Academy. Parck acknowledged and informed Foss of the change. Foss later sent a message to Commandant Deenlark of the Royal Imperial Academy, informing him that Thrawn was already a capable soldier, and only needed an orientation in Imperial procedures, equipment, and terminology. Foss also instructed Deenlark that Thrawn was to graduate with a rank of a lieutenant, instead of the usual rank of an ensign, in order to get him to a command position more quickly.