At last count, more than 80 U.S. submarines recorded some type of actual "friendly fire" incident in which they were involved during their WWII war patrols. From being attacked by Allied bombers, depth-charged by U.S. ships or fired upon by armed Allied merchant ships, submariners quickly came to understand the bitter truth of the maxim: 'The submarine has no friends.' While the majority of submarines and their crew escaped with little more than bruised egos or minor injuries, three submarines and their crews were lost to friendly fire. For the first time in book format, a serious and most comprehensive research effort has gone into capturing all such "friendly fire" incidents involving U.S. submarines during World War II. Compiled through relentless research by the co-authors, their stories of loss and survival by "other than the enemy" is presented within these pages.