High Quality Content by WIKIPEDIA articles! Conrad (25 March 1252 – 29 October 1268), called the Younger or the Boy, but usually known by the diminutive Conradin (German: Konradin, Italian: Corradino), was the Duke of Swabia (1254–1268, as Conrad IV), King of Jerusalem (1254–1268, as Conrad III), and King of Sicily (1254–1258, de jure until 1268, as Conrad II).