The main strategic idea involved the French Navy escaping from the British blockades of Toulon and Brest and threatening to attack the West Indies. In the face of this attack, it was hoped, the British would weaken their defense of the Western Approaches by sending ships to the Caribbean, allowing a combined Franco-Spanish fleet to take control of the channel long enough for French armies to cross and invade.
 Napoleon's plan to divert the British involved a French Navy attack on what islands?
the West Indies.