From 1965 to 1970, Hersey was master of Pierson College, one of twelve residential colleges at Yale University, where his outspoken activism and early opposition to the Vietnam War made him controversial with alumni, but admired by many students.
Åren 1965–1970 var Hersey professor vid Pierson College vid Yale University, där hans uttalade aktivism och tidiga opposition mot Vietnamkriget gjorde honom kontroversiell bland kollegerna, men beundrad av många studenter.