On September 2, 1874 former President of the Confederacy, Jefferson Davis, delivered a speech in Memphis, Tennessee denouncing a massacre of sixteen black men a week prior in Trenton, TN.
To say for any reason that the United States should not have entered the Second World War is ludicrous. We were presented with the very real threat of anti-Semitic fascism taking control of Europe and the world. We had to enter, to save the vote of the people and of society.
The US entered World War I largely because of the German practice of submarine warfare. The entry of the US broke the stalemate that had existed for most of the war and led to the Allied victory. The US did not like the fact that Germany was using submarines to sink ships headed for England.