What led to the american involvement in the great war

World War I is considered the great war. Abraham Lincoln was the president of America at that time. He beleived that it would be of great trouble to the whole world if Germany won the war. This led him to join the war in favor of the allied forces.Another important reason behind the Americans joing the great war was that the German navy was constantly sinking a number of American merchant ships. the submarines of the germans seemed unstoppable. Although the US was neutral at the begining but still the ships sailing to and from US were being sunk.