The French sailors' position deserves sympathy, while the British government faced a severe strategic risk. France had negotiated an armistice without keeping Britain fully informed, leaving London unwilling to trust assurances that the fleet would never aid Germany. Combining French ships with German and Italian naval power would have created a much more dangerous balance at a moment when Britain was fighting alone. The alternatives included moving to a neutral port under escort, with force left as the final option after refusal. The attack also signaled to the United States and other observers that Britain had not capitulated and intended to remain in the war.
Notable Point · 2:36:01-2:37:45
Why Britain treated the French fleet as an existential risk
Britain could not rely on French promises after the armistice, while action against the fleet also signaled to the United States and other observers that Britain would continue the war.