1. 'Not what it could or should be': Britain's shipping situation -- 2. 'Beyond our power without your help': Britain's Battle of the Atlantic -- 3. 'But westward, look, the land is bright': American shipping assistance from neutrality to belligerency, March 1941-November 1942 -- 4. Roosevelt's promise: 'Your requirements will be met' -- 5. The Casablanca Conference and its aftermath: a 'most curious misunderstanding' -- 6. Reaping the whirlwind: the perils of impending victory -- Postscript and conclusions -- Appendices.