Brest combined a protected deep-water harbor with immediate access to several strategically important routes. A fleet leaving it could work eastward up the English Channel, enter the Atlantic, threaten Cornwall or Wales, or operate toward Ireland. That flexibility made the port a recurring base for invasion schemes and a central British planning problem. Its value came from geography, however, not from an automatic French advantage at sea.
Chapter · 24:13-29:25
Why Brest threatened Britain
Brest offered a deep-water base from which a French fleet could reach the Channel, Atlantic, Ireland, or Britain’s western coast.