Who is William Shawn from Letters of E. B. White and what is their importance?

William Shawn was the second editor of The New Yorker and successor to founder Harold Ross after his untimely death, Shawn has big shoes to fill and a talented staff to win over. Using the same kind of supportive and friendly style while maintaining high journalistic standards, Shawn succeeds and White develops a close relationship with him that involves the exchange of many letters—even after White leaves the magazine.