Ever since the failure of the last Arab attempt to conquer the Byzantine capital Constantinople, regular, almost annual raids were undertaken by the Caliphate's forces into Byzantine Asia Minor. In 782, a major invasion, led by the Abbasid heir apparent, the future Harun al-Rashid (r. 786–809), resulted in a humiliating settlement for Byzantium, which was forced to sue for a truce in exchange for an annual payment of 160,000 gold nomismata.[1] In 785, Empress-regent Irene of Athens resolved to cease the payment of the tribute, and warfare recommenced.