Brest's geography created an information asymmetry as well as a navigational problem. Shore observers could not see far enough into the offing to know whether the main British squadron was actually present. If a few ships maintained the appearance of an inshore watch and signalled toward the horizon, French commanders had to assume that a larger force might be waiting beyond sight. The deception would eventually be tested, but even a delay of several days could buy the Royal Navy time to restore the blockade.
Notable Point · 20:17-20:55
An inshore watch could bluff a full blockade
French observers could see the inshore ships but not the main force beyond the horizon, letting a small watch imply that the whole Western Squadron remained nearby.