After the events of The Dark Knight Strikes Again, Batman (or Crazy Steve, if you prefer) does more crazy stuff around Gotham. However, he had the bright idea to do what would inadvertently mark the beginning of the war that would eventually have JUNO decide that the human race needed to be destroyed. What happened exactly is unknown, but it was assumed that he decided to kidnap someone on the researching team, and says they need to give him the crystals to get him back. They reluctantly agree, and Batman goes back to Gotham and secretly gives it all to the police (without them knowing, of course). However, other countries get wind that something that is useful for a purpose was sent to America, and they declare war for it. It proves devastating, and as stated above, JUNO decides humanity