John I of France

John the Posthumous
Tomb Effigy of John the Posthumous
King of France and Navarre
Reign	15–20 November 1316
Predecessor	Louis X and I
Successor	Philip V and II
Born	(1316-11-15)15 November 1316 Paris, France
Died	20 November 1316 (aged 5 days) Paris, France
Burial	Saint Denis Basilica
House	Capet
Father	Louis X of France
Mother	Clemence of Hungary

John I (15–20 November 1316), called the Posthumous, was King of France and Navarre, as the posthumous son and successor of Louis the Quarreler, for the five days he lived in 1316. Although considered a king today, his status was not recognized until chroniclers and historians in later centuries began numbering John II, thereby acknowledging John I's short reign. If his reign is recognized, it is the shortest of any French king. He is also the only person to be considered King of France since birth and, thus, the youngest person to be King of France and the only to hold the title for their entire life.

John reigned for five days under the regency of his uncle Philip the Tall, until his death on 20 November 1316. The infant King was buried in Saint Denis Basilica. He was succeeded by Philip, whose contested legitimacy led to the re-affirmation of the Salic law, which excluded women from the line of succession to the French throne.

The child mortality rate was very high in medieval Europe and John may have died from any number of causes, but rumours of poisoning spread immediately after his death, as many people benefited from it and as John's father died himself in strange circumstances. The cause of his death is still not known today.

The premature death of John brought the first issue of succession of the Capetian dynasty. When Louis the Headstrong, his father, died without a son to succeed him, it was the first time since Hugh Capet that the succession from father to son of the kings of France was interrupted. It was then decided to wait until his pregnant widow, Clementia of Hungary, delivered the child. The king's brother, Philip the Tall, was in charge of the regency of the kingdom against his uncle Charles of Valois. The birth of a male child was expected to give France its king. The problem of succession returned when John died five days after birth. Philip ascended the throne at the expense of John's four-year-old half-sister, Joan, daughter of Louis X and Margaret of Burgundy.