Message to King Victor Emmanuel of Italy on the Poland Crisis.
"Again a crisis in world affairs makes clear the responsibility of heads of nations for the fate of their own people and indeed of humanity itself. It is because of traditional accord between Italy and the United States and the ties of consanguinity between millions of our citizens that I feel that I can address Your Majesty in behalf of the maintenance of world peace.
"It is my belief and that of the American people that Your Majesty and Your Majesty's Government can greatly influence the averting of an outbreak of war. Any general war would cause to suffer all nations whether belligerent or neutral, whether victors or vanquished, and would clearly bring devastation to the peoples and perhaps to the Governments of some nations most directly concerned.
"The friends of the Italian people and among them the American people could only regard with grief the destruction of great achievements which European nations and the Italian nation in particular have attained during the past generation.
"We in America, having welded a homogeneous nation out of many nationalities, often find it difficult to visualize the animosities which so often have created crises among nations of Europe which are smaller than ours in population and in territory, but we accept the fact that these nations have an absolute right to maintain their national independence if they so desire. If that be sound doctrine then it must apply to the weaker nations as well as to the stronger.
"Acceptance of this means peace, because fear of aggression ends. The alternative, which means of necessity efforts by the strong to dominate the weak, will lead not only to war, but to long future years of oppression on the part of victors and to rebellion on the part of the vanquished. So history teaches us.
"On April fourteenth last I suggested in essence an understanding that no armed forces should attack or invade the territory of any other independent nation, and that, this being assured, discussions be undertaken to seek progressive relief from the burden of armaments and to open avenues of international trade including sources of raw materials necessary to the peaceful economic life of each nation.
"I said that in these discussions the United States would gladly take part. And such peaceful conversations would make it wholly possible for Governments other than the United States to enter into peaceful discussions of political or territorial problems in which they were directly concerned.
"Were it possible for Your Majesty's Government to formulate proposals for a pacific solution of the present crisis along these lines you are assured of the earnest sympathy of the United States.
"The Government of Italy and the United States can today advance those ideals of Christianity which of late seem so often to have been obscured.
"The unheard voices of countless millions of human beings ask that they shall not be vainly sacrificed again."
Franklin D. Roosevelt, Message to King Victor Emmanuel of Italy on the Poland Crisis. Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/209884