First Usages
The circumflex first appeared in written French in the 16th century. It was borrowed from Ancient Greek, and combines the acute accent and the grave accent. Grammarian Jacques Dubois (known as Sylvius) is the first writer known to have used the Greek symbol in his writing (although he wrote in Latin).
Several grammarians of the French Renaissance attempted to prescribe a precise usage for the diacritic in their treatises on language. The modern usage of the circumflex accent became standardized in the 18th or 19th century.
Read more about this topic: Use Of The Circumflex In French