 O’Hara has authored, co-authored or edited twelve books and contributed articles to publications, including "Naval War College Review", "MHQ", "Storia Militare", "Warship", "Seaforth World Naval Review", "America in WWII", "World War II", and "World War II History".He was an assistant editor of ABC Clio's "Encyclopedia of World War II at Sea" and has written introductions to two volumes of the "U.S.Naval Operations in World War II" series by Samuel E. Morison republished by the U.S.