British nightmare planning assumed simultaneous war with Germany, Italy, and Japan but still counted on France. The French fleet broadly balanced the Italian navy even though each side possessed different strengths and weaknesses. That left Britain to concentrate its own main effort against Germany and Japan, a two-ocean problem it believed it could manage. Removing France weakened the coalition, added Italy directly to the Royal Navy's burden, and broke the strategic model on which prewar force planning rested.
Chapter · 1:16:06-1:17:16
The French fleet is the balance against Italy
The conclusion identifies French naval power as the element that made Britain's three-enemy war concept manageable.