Robert Leckie was born on December 18, 1920, in Philadelphia, Pennsylvania. He grew up in Rutherford, New Jersey, and began his career as a writer in high school, working as a sports writer for The Bergen Evening Record in Hackensack, New Jersey.

On January 18, 1942, Leckie enlisted in the United States Marine Corps. He served in combat in the Pacific theater as a scout and machine gunner in H Company, 2nd Battalion, 1st Marines Regiment, 1st Marine Division. Leckie saw combat in the Battle of Guadalcanal and the Battle of Cape Gloucester, and was wounded by blast concussion in the Battle of Peleliu. He returned to the United States in March 1945 and was honorably discharged shortly thereafter.

Following World War II, Leckie became a well-known author of military history. He is best known for his bestselling book Helmet for My Pillow, published in 1957, which recounts his wartime experiences in the battles of Guadalcanal and Peleliu. This work served as a source for the television series The Pacific, released in 2010.