German preparations gathered improvised craft that looked less organized than the mixed fleet used at Dunkirk. The Kriegsmarine had also lost much of the destroyer force painstakingly built before the war during the Narvik battles. That left barges and transports exposed to British battleships, cruisers, destroyers, submarines, and motor torpedo boats approaching from both ends of the Channel. German aircraft might damage the counterattack, but the likely exchange remained catastrophic for an invasion force caught at sea without adequate escorts.
Notable Point · 1:48:27-1:52:43
Sea Lion lacked a protected invasion fleet
Improvised barges and the destruction of much of Germany's destroyer force at Narvik left Sea Lion without the shipping and escort strength needed to cross under attack.