In mid-February 1944 Marian Elizabeth Smith, a young Wisconsin woman, met Marine Corps Lieutenant Eugene T. Petersen on the passenger train, El Capitan, as it made its 42-hour run from Los Angeles to Chicago. After a brief acquaintance, he left the United States to join the Third Marine Division on Guam and eventually to take part in the battle for Iwo Jima in February and March of 1945. The collected letters of their subsequent 18-month correspondence...