Henry II’s story, and that of his wife’s – Catherine de Medici, began when Francis I was captured by the Spanish ruler and Holy Roman Emperor, Charles V.
As part of the conditions for Francis’ release from captivity (his ransom), he had to exchange his two young sons (Henry and Francis) in his place, and Henry had to marry the niece of Pope Clement VII.
The boys were held for in captivity for four years.
Henry was forced to marry Catherine de Medici at 14 years old. It was not a good marriage. Henry was disrespectful of Catherine in very significant ways.
Henry II died of a mishap. Catherine, as regent for her minor sons, was manipulated by the Church and the Catholic nobles, into making decisions which were detrimental to France.
These decisions sent France into the Wars of Religion.