Franklin D. Roosevelt
Roosevelt was the president through WWII. That was no easy task. Some history teachers and sociologists consider Roosevelt to be the most important president in American history.
Before the Term Limit
Before there was an established two-term limit for the president, Roosevelt pioneered America from 1933-1945, serving four terms total. His tenure ended when he died in office in 1945. His experience and knowledge of the practices of law in America solidified him as one of the most intelligent presidents America has ever seen. Additionally, Roosevelt had an IQ of 150.