(əkĭl'ēz) , 1414–86, elector of Brandenburg (1470–86); third son of Elector Frederick I. He succeeded his brother in 1470. Anxious to consolidate Hohenzollern power in Brandenburg, he issued (1473) the Dispositio of Achillea, which decreed that the title of elector should pass to the eldest son. This established the law of primogeniture in Brandenburg. The Dispositio remained in force until 1918.