O’Donnell is a bestselling author, critically acclaimed military historian and an expert on elite units. The author of twelve books, including: Washington’s Immortals: The Untold Story of an Elite Regiment Who Changed the Course of the Revolution, The Unknowns, First SEALs, Give Me Tomorrow, The Brenner Assignment, We Were One, Beyond Valor, and Dog Company, he has also served as a combat historian in a Marine rifle platoon during the Battle of Fallujah and speaks often on espionage, special operations, and counterinsurgency. He has provided historical consulting for DreamWorks’ award-winning miniseries Band of Brothers and for scores of documentaries produced by the BBC, the History Channel, and Discovery and is the recipient of several national awards. He also regularly contributes to several national publications and shows.