不戦条約
At Yale University, Ferrell earned a master's degree in 1948 and a Ph.D. in 1951, working under the direction of Pulitzer Prize-winning historian Samuel Flagg Bemis. A student of the Kellogg–Briand Pact, a 1928 international agreement in which signatory states promised not to use war to resolve their disputes, his dissertation "The United States and the Origins of the Kellogg–Briand Pact", won Yale's John Addison Porter Prize for original scholarship.