Just a side note:   After the war the invasion of England (Operation Sealion) was played out as a war game by senior military members of both sides. The Germans (Adolf Galland Luftwaffe fighter ace, was one of the Germans who participated) they all admitted that the invasion would not have succeeded with the type of troop barges and boat transport they planned to use to transport across the channel. After an initial victory on the beaches their supplies would have never been landed in enough quantity to support a main force for more than two or three weeks; even if they captured the ports of Dover, Folkestone or Shoreham they would not have been in usable condition to large shipping for months. The German Airforce could not supply enough heavy equipment and munitions to support the airborn landings, and the whole thing would have failed before reaching London. There is a book on the subject it makes interesting reading.