The term 'Father of France' is a title given to King Louis XIV, who reigned from 1643 to 1715. He was the longest-reigning monarch in European history and is often referred to as the 'Sun King'. His reign saw the expansion of French power and influence in Europe, and he is credited with transforming France into a major European power. The crossword solution for this term is 'PERE', which is the French word for father.