The fourth anniversary reunion on the steps of Eckhart Hall at the University of Chicago, Dec. 2, 1946. Back row, left to right: Norman Hilberry (Argonne's second director), Samuel Allison, Thomas Brill, Robert Nobles, Warren Nyer and Marvin Wilkening. Middle row: Harold Agnew, William Sturm, Harold Lichtenberger, Leona W. Marshall and Leo Szilard. Front row: Enrico Fermi, Walter Zinn (Argonne's first director), Albert Wattenberg and Herbert Anderson.