Grandfather Leopold Klein, born in Chicago but too sick to leave Berlin at the U.S. entry into WWI, wrote in his diary:
"This 'World War' must end soon. When it does come to an end, the principles of justice, mercy and, above all, reason - which dictates all the rest - must guide the nations concerned in the establishment of peace. Otherwise, these nations will only lay the foundation for later, and greater, world conflict.... If a true peace is not made when the shooting stops, the result may be a truly worldwide conflict - thrusting its horror to the four corners of the earth, a World War which will be the greatest catastrophe humanity has yet experienced." (Berlin, 1917)
