Kron Stone and his gang murdered Jake Gallows' mother, brother and sister-in-law. He was himself seriously injured.
After recovering, Jake, disgusted by the sentence for Stone, had come across and stolen, from the Public Eye, archives of the original Punisher's War Journal. The last page bore the challenge: "You who find this, I charge you to carry on my work." Soon after, he became the new Punisher.
Under his new vigilante identity, Jake seemingly killed Stone, but decided to continue his rampage and collaborate with his side-kick Matt Axel on an arsenal, a prison (the Punishment Hotel), and a Molecular Disintegration device to terminate unrepentant criminals.