Well Woodrow Wilson gave us a major break from the earlier notion of non-interference, especially in European affairs. The Mexican War and to a lesser extent the Spanish American War were part of our hemispheric expansion, or "manifest destiny". It is my belief that saving the British system was the main objective for World War I, not "making the world safe for democracy".

Pope Benedict XV did everything he could to prevent and stop the war, but the national grudges were just too strong. Europe and Christian civilization paid a price that has never been recovered. For better or worse four empires collapsed; the communists led by Lenin came to power in Russia.  The war broke the social contract in Britain.

World War II propelled the US to great power as world markets fell into our lap due to destruction of friends and foes. Those days are gone now. Our place in world affairs is open to question.