He was in charge of the royal stables, the transport of the king and his ceremonial entourage (heralds, men of arms, musicians, etc.).
As well as the superintendence of the royal stables, he had that of the retinue of the sovereign, also the charge of the funds set aside for the religious functions of the court, coronations, etc.
The authority of the Grand Écuyer also extended across the realm, as he oversaw horse breeding and provincial military academies created to educate young nobles.
Distinct from this officer and independent of him, was the first equerry ("Premier Écuyer de France"), who had charge of the horses which the sovereign used personally (the "Little Stable" or "petite écurie"), and who attended on him when he rode out.
The Grand Écuyer had the privilege of bearing the king's sword in ceremonies outside of royal residences.