In the 1930s a band of smart and able young men, some still in their twenties, helped Franklin D. Roosevelt transform an American nation in crisis. They were the junior officers of the New Deal. Thomas G. Corcoran, Benjamin V. Cohen, William O. Douglas, Abe Fortas, and James Rowe helped FDR build the modern Democratic Party into a progressive coalition whose command over power and ideas during the next three decades seemed politically invincible...