The invasion plan received a crippling blow in November, when the French Brest Squadron was heavily defeated at the Battle of Quiberon Bay.
 Conflans had sailed from Brest on 15 November heading a hundred miles down the coast to Quiberon Bay, where the invasion army was now waiting to board his transports.
Conflans' fleet became caught in a storm which slowed them down and allowed the pursuing British under Sir Edward Hawke a chance to catch up with them.

Meeting at the mouth of Quiberon Bay on 21 November, the two fleets closed in on each other.
 Conflans initially formed a line of battle and prepared to engage, but then changed his mind and his ships raced to take shelter in the bay.
Hawke pursued, taking a high risk in the middle of a violent storm, and captured or drove ashore five French ships.
The remainder managed to find shelter in the bay.
They were now blockaded in by the British fleet, and most were abandoned and their guns taken off them.
Only three ships ever sailed again, a devastating setback to the French Channel fleet.
The crushing defeat at Quiberon Bay ended any real hope of a major invasion of the British Isles.
The invasion plan received a crippling blow in November, when the French Brest Squadron was heavily defeated at the Battle of Quiberon Bay.  Conflans had sailed from Brest on 15 November heading a hundred miles down the coast to Quiberon Bay, where the invasion army was now waiting to board his transports. Conflans' fleet became caught in a storm which slowed them down and allowed the pursuing British under Sir Edward Hawke a chance to catch up with them.
Meeting at the mouth of Quiberon Bay on 21 November, the two fleets closed in on each other.  Conflans initially formed a line of battle and prepared to engage, but then changed his mind and his ships raced to take shelter in the bay. Hawke pursued, taking a high risk in the middle of a violent storm, and captured or drove ashore five French ships. The remainder managed to find shelter in the bay. They were now blockaded in by the British fleet, and most were abandoned and their guns taken off them. Only three ships ever sailed again, a devastating setback to the French Channel fleet. The crushing defeat at Quiberon Bay ended any real hope of a major invasion of the British Isles.
Planned French invasion of Britain (1759)