The Joker- Batman Vol. 1 #251 "The Joker's Five Way Revenge!"
"His life is mine... I can crush the breath out of him... effortlessly! I can, at last, triumph! But such a hollow victory--! It was mere luck that caused my attack on him to succeed. I'd always envisioned my winning as a result of cunning... at the end of a bitter struggle between the Batman and Myself-- him using his Detective Skills and me employing the divine gift men call Madness!... No! Without the game that the Batman and I have played for so many years, winning is nothing! He shall live... until I can destroy him properly!" - The Joker
Batman Vol. 1 #251 is one of the most important issues, in my opinion, in comic book history. The story follows The Joker, having broken out of prison, as he makes good on a murderous vow of revenge. The gang of miscreants The Joker surrounded himself with had proved faulty and one of the five members was a rat in need of extermination. As there is was no logical way of determining which gang member had betrayed him, The Joker decides to track down all five.
Batman is alerted when the first smiling corpse is found. He immediately recognizes the dead man's connection to The Joker and begins making his rounds, trying to protect the gang members from their fate. To Batman's dismay, The Joker is able to murder most of them quite easily.
One gang member goes into protective custody and is killed by drinking water that has been poisoned with Joker Venom. The third member is tricked by The Joker into believing the two men are on good terms. The Joker gifts the gang member a cigar and leaves. When the man tries to light the cigar it explodes- killing the gang member and destroying his home. The fourth man is hung by The Joker while Batman is unconscious.
When The Joker and Batman finally do meet, Batman is disoriented after being attacked by the fourth gang member. The Joker wins their fight and subdues Batman quite easily. The Joker places his foot on Batman's neck and debates killing him. This is the most important part of the story, in my opinion, because The Joker chooses not to.
The Joker chooses to wait and beat Batman when the fight is fair. The Joker does not want to win in a cheap way and, instead, wants to annihilate Batman in his prime. Bruce Wayne's life is spared because The Joker wants him to be fully aware of his defeat.