Admiral de Grasse had the option to attack British forces in either New York or Virginia; he opted for Virginia,
arriving at the Chesapeake at the end of August. Admiral Graves learned that de Grasse had sailed from the West Indies
for North America and that French In spite of the British warning, the French appearance in Rio's harbour on 12 September was a surprise.
The British news, when it arrived in August, had led Governor Francisco de Moraes de Castro to call out his militia
and increase preparedness, and rumours of sails off Cabo Frio in early September had again raised the alert.
However, on 11 September the governor ordered the militia to stand down, just as Duguay-Trouin was preparing
his approach to the harbour.The commander of Le Lys, Courserac, led the squadron directly in the Bay of Rio,
between the forts lining the harbour entry, and straight at seven Portuguese warships that were anchored there.
The Portuguese fleet commander, admiral Gaspar da Costa, could do nothing but cut the cables in hopes of getting
his ships moving. Three of battleships grounded and were destroyed by the Portuguese to prevent their capture;
the fourth was taken by the French and burned. Fire from the forts, undermanned after the order to stand down,
did some damage to the French fleet, inflicting 300 casualties before the ships passed out of range.