Frederick III the Simple

Frederick III or IV (1 September, 1341 – 27 January, 1377), called the Simple, King of Sicily from 1355 to 1377, was the second son of Peter II of Sicily and Elisabeth of Carinthia. He succeeded his brother Louis. The documents of his era call him the "infante Frederick, ruler of the kingdom of Sicily," without any regnal number.

"Frederick the Simple" is often confused with an earlier Sicilian monarch, Frederick II, who chose to call himself "Frederick III", even though he was actually only the second King Frederick to occupy the Sicilian throne, as also this Fredrick has been dubbed by later generations of genealogists and historians as Frederick III.

The beginning of Frederick III's reign was plagued by intermittent wars with the Kingdom of Naples and also by the Black Death, to which his elder brother and predecessor had succumbed. In 1372 he was able to come to peace terms with Naples and the Papacy and was titled as a Tributary King of "Trinacria."

He appointed his uncle, Roland, to act on his behalf in the Duchy of Athens and Neopatria.

On 11 April, 1361, Frederick married his first wife Constança of Aragon, daughter of Peter IV of Aragon. They had only one daughter, Mary. On 17 January, 1372, Frederick married secondly Antonia of Balzo. There were no children from this marriage.