In August 1437, the Portuguese expeditionary force, under the leadership of Henry the Navigator, set out to seize Tangier. Ferdinand brought his household and Aviz knights with him, choosing as his personal banner an emblazoned image of the Archangel St. Michael. The Tangier campaign proved to be a disastrous fiasco. Henry impetuously launched a series of assaults on the walls of Tangier with no success, while allowing his siege camp to be encircled by a Moroccan army rushed north by the Wattasid strongman Abu Zakariya Yahya al-Wattasi, governor of the Marinid palace of Fez (called "Lazeraque" by the Portuguese chroniclers). The Portuguese besiegers, now besieged and unable to break out, were starved into submission.