...President Roosevelt's proposal to use American influence for the purpose of bringing together the leading European Powers to discuss the chances of a general settlement, this of course involving however tentatively the might power of the United States, was rebuffed by Mr. Chamberlain. 
...
No one can measure in retrospect its effect upon the course of events in Austria and later at Munich. We must regard its rejection--for such it was--as the loss of the last frail chance to save the world from tyranny otherwise than by war. That Mr. , with his limited outlook and inexperience of the European scene, should have possessed the self-sufficiency to wave away the proffered hand stretched out across the Atlantic leaves one, even at this date, [1948] breathless with amazement. The lack of all sense of proportion, and even of self-preservation, which this episode reveals in an upright, competent, well-meaning man, charged with the destinies of our country and all who depended upon it, is appalling. One cannot to-day even reconstruct the state of mind which would render such gestures possible. 

Winston S. Churchill, The Second World War, Volume 1 The Gathering Storm, p200.