As an upperclassman at Harvard, Kennedy became a more serious student and developed an interest in political philosophy. In his junior year, he made the Dean's List .  In 1940, Kennedy completed his thesis, "Appeasement in Munich", about British participation in the Munich Agreement . The thesis became a bestseller under the title Why England Slept .  In addition to addressing Britain's failure to strengthen its military in the lead-up to World War II, the book also called for an Anglo-American alliance against the rising totalitarian powers. While Kennedy became increasingly supportive of . intervention in World War II, his father's isolationist beliefs resulted in the latter's dismissal as ambassador to the United Kingdom, creating a split between the Kennedy and Roosevelt families.