 French and British patrol frigates each spotted the other's fleet around 9: 30 am; both at first underestimated the size of the other fleet, leading each commander to believe the other fleet was the smaller fleet of Admiral de Barras. When the true size of the fleets became apparent, Graves assumed that de Grasse and Barras had already joined forces, and prepared for battle; he directed his line toward the bay's mouth, assisted by winds from the north-northeast.
