America entered world war one in 1917 due to several independent and collective factors. Such as the sinking of the Lusitania and Germanys secret collaboration with Mexico.
Ideological/moral desire to uphold democracy
Theodore Roosevelt and Henry Cabot Lodge believed that America should have a world role.William Jennings Bryan was a noted orator with strong support in the country for his pacifist view. He resigned as secretary of state in 1915. Many Americans disliked the political system of Imperial Germany, particularly the focus on military methods rather than democratic ones. The USA declared war on Germany on 6th April 1917 with a ringing pronouncement that the USA would make the world “safe for democracy”. The war had become more ideological clear-cut with the morally superior democratic Entente Powers (Britain, France and Russia) fighting the immoral militaristic Central Powers (Germany and Austria-Hungary).
German aggression
In May 1915, a German submarine sank the British ocean liner Lusitania killing 1,200 people of which 128 were Americans. German invasion of Belgium in September 1914. In 1916 the German foreign minister Alois Zimmermann, secretly proposed an alliance between Germany and Mexico. What became known as the ‘Zimmerman Telegram’, promised German support for Mexico against the USA. By the end of 1916, Germany’s economic position was so desperate it decided to launch unrestricted submarine warfare in the Atlantic. The Germans were the first nation to use poison gas in the trenches on the Western Front. The German High Command announced a resumption of unrestricted submarine warfare based on the view that if such an act provoked America to declare war, it would t ...