What is the greatest example of self-defeat in naval history?
Short answerLissa, failed invasions of Japan, and Force Z are suggested, with the qualification that Tegetthoff actively exploited the Italian mistakes at Lissa.
NotesThe Italian fleet at Lissa is one candidate for a self-inflicted defeat, although Tegetthoff also deserves credit for exploiting its mistakes. Attempts to invade Japan provide another example, with insufficient attention to weather cycles blamed for avoidable losses. Force Z illustrates communication errors accumulating into a serious operational problem. These are suggested examples rather than a settled ranking of naval defeats.