8. John I was the youngest King of France and the only monarch to have carried the title from birth
John I, also known as John the Posthumous, was King of France and Navarre between November 15, 1316, and November 20, 1316. The youngest person to ever hold the throne of France, and the only monarch to retain the title from birth, John was also the only person to reign for the entirety of their lifespan in addition to possessing the shortest reign of any French king. The first son of Louis X, born to Louis’ second wife Clementia, Louis died whilst his wife was still pregnant. This uncertainty raised complicated questions surrounding the succession, as a son would have primacy over Louis’ 3-year-old daughter, Joan of Navarro, whilst a daughter would merely be a competing claim to the throne. As a result, and for the first time in over three hundred years since the election of Hugh Capet, the French royal succession was interrupted and halted, with Louis’ brother Philip the Tall named as regent for five months in anticipation of the royal birth.
Despite the birth of a son on November 15, and hence the immediate ascension of the newborn John to the throne, the question of the succession was far from solved as the infant king died just five days later. The reasons behind his sudden death remains shrouded, as infant mortality was indeed immensely high in medieval Europe and John might simply have died of natural causes. Perhaps understandably, given the timing as well as the suspicious demise of his regal father, it was (and continues to be) speculated that the child was poisoned on behalf of his uncle, regent, and ultimately successor, Philip. In the wake of his nephew’s death, Philip ascended to the throne as the fifth of his name and enshrined the continuation of Salic law in the French succession: the exclusion of immediate female descendants from the line of succession in preference of any living male relatives.