8. Woodrow Wilson
Wilson served two terms as President from 1913-1921. During his first term, he enacted many major pieces of legislation including the Underwood Act, the Federal Reserve Act, and establishing the Federal Trade Commission.
But his most important decision as President came in 1917 when he concluded that America could no longer remain neutral in the ongoing World War and declared war on Germany. In just a few months, the Americans helped the Allies get the advantage and in November of 1918, the Germans signed the Armistice that ended WWI.