#onThisDay in 1956 #TheChallengersOfTheUnknown debuted in #ShowcaseComics #6 #FourAdventurersWhoSurviveAPlaneCrash & #bandTogetherAsCompatriots #livingOnBorrowedTime headquartered at #ChallengersMountain #JackKirby #QuartetConcept #sortaBorrowed #FiveYearsLater @Marvel as #TheFantasticFour