been widely referred to as "one of the founders of metalcore." History Early years (1999–2000) Killswitch Engage formed when the two metalcore bands, Overcast and  Aftershock disbanded during the late 1990s. [1]  Following the disbandment of Overcast in 1998, bassist  Mike D'Antonio   jammed  with Aftershock guitarist  Adam Dutkiewicz . Dutkiewicz