In 1410, King Martin of Aragon died without a legitimate heir to succeed him. As a result, several candidates disputed the Aragonese throne; for two years rival contenders deployed diplomatic and military efforts to overcome their rivals. Eventually, only one succeeded: Ferdinand of Trastámara. However, his election as king of Aragon had yet to be legitimised and consolidated. This chapter explains how, in the two years following the death of King Martin until the election of the new monarch (1410–12), and then throughout his reign (1412–16), Ferdinand I employed a communication strategy based on propaganda, first to guarantee his election as king and, later, to consolidate the hold of his dynasty on the throne. The chapter then examines the evolution of this process of legitimisation in the years that followed, to best suit the needs of the dynasty in the reign of Alfonso V (1416–58), and beyond.