Ferdinand the Holy Prince (Portuguese: Fernando o Infante Santo; September 29, 1402 – June 5, 1443), sometimes called the "Saint Prince" or the "Constant Prince", is an infante of the Kingdom of Portugal.
He is the youngest of the "Illustrious Generation" of fifteenth-century Portuguese princes of the House of Aviz and was lay administrator of the Knightly Order of Aviz.
In 1437, Ferdinand participates in the disastrous Siege of Tangier led by his older brother Henry the Navigator.
In the aftermath, Ferdinand is handed over to the Marinid rulers of Morocco as a hostage for the surrender of Ceuta, terms negotiated in a treaty by Henry.
At first, Ferdinand is held in relative comfort as a noble hostage in Asilah, but when it becomes apparent that the Portuguese authorities have no intention of fulfilling the terms of the treaty and yielding Ceuta, Ferdinand's status is downgraded and he is transferred to a prison in Fez, where he is subjected to much harsher incarceration conditions and humiliations by his Moroccan jailers.
Negotiations for his release continue on-and-off for years, but come to naught, and Ferdinand eventually dies in captivity in Fez on June 5, 1443.
A popular cult quickly develops in Portugal around the figure of "the Holy Prince" (O Infante Santo), strongly encouraged by the House of Aviz.
Ferdinand remains a "popular saint" by Portuguese tradition, neither beatified nor canonized by the Roman Catholic Church.
