[2] According to chronicler Jean de Joinville, an old knight acted as midwife during John's birth.

Two days prior to his birth, the king was captured by the Mamluks which was the reason to name the child Tristan due to the triste occasion.

John subsequently spent his childhood in the Holy Land where his siblings Peter (1251) and Blanche (1253) were born.

[4] Two years later, John accompanied his father during the Eighth Crusade,[2] which reached Tunis in July after setting out from Cagliari on Sardinia.

His widow married again in 1272 with Robert III of Flanders;[3] the county of Valois, his prerogative, returned to the Crown.