"Cronkite's War: His World War II Letters Home" is scheduled for release Tuesday, CBS News reported.
The collection was assembled by Cronkite's grandson, Walt, working with Maurice Isserman, his history professor at Hamilton University in New York.
"I went down to the University of Texas with my father after my grandfather passed away," Walt Cronkite said in an interview Saturday on CBS. "We discovered this treasure trove of all these letters he wrote home to my grandmother several times a week during World War II, and we thought it was just fascinating stuff."
Walter Cronkite was 26 and newly married when he went to Europe in 1942. He would not return to his wife, Betsy, for three years.
One of the U.S. reporters selected to fly on bombing raids with the Air Force, Walter Cronkite in one letter describes getting shot down behind enemy lines. His grandson said the letter shows he "was truly, truly, scared."
Another letter shows Walter Cronkite turned down an offer from Edward R. Murrow of CBS during the war. He remained with UP, covering the Nuremburg trials and serving as Moscow bureau chief, until 1950, when he joined CBS.