The Allies are doing some math of their own, and they are scared shitless. There are 100 German U-boats in the Atlantic now, operating mostly from Lorient and Bordeaux, and they are slaughtering convoys in the North Atlantic with such efficiency that it’s not even combat , just a Lusitanian-level murder spree. They are on a pace to sink something like a million tons of shipping this month, which Waterhouse cannot really comprehend. He tries to think of a ton as being roughly equivalent to a car, and then tries to imagine America and Canada going out into the middle of the Atlantic and simply dropping a million cars into the ocean—just in November. Sheesh!