Ennis has been working on the story for over a year and a half now. Word first came down in August 2013 that things were in "very early stages." Then in January last year, Ennis told CBR that he'd finished writing the tale and that his "Punisher MAX" collaborator Goran Parlov was coming on to draw it. On Saturday, Ennis finally revealed more details at London Super Comic-Con (via Bleeding Cool).
At a panel discussion with Avatar Press publisher William Chirstensen, Ennis said the series will be titled "The Platoon" and released under the Marvel MAX banner. According to Ennis, the story will follow Frank Castle on his first tour of duty in Vietnam. That means it will be way before he became The Punisher, so don't expect any giant white skulls on his body armor.
“So you were being sneaky; you’re just writing a war story, but calling it the Punisher?” asked Christensen. “Yup," was Ennis' reply.
Ennis also revealed he's working on "interesting stuff with Alan Moore" for Avatar, and provided more details on his forthcoming Section 8 for DC Comics. Section 8 will be a six-issue mini where Six Pack, Dogwelder, and five others of the team from "Hitman" get back together, even some who are already dead. When Six Pack has trouble finding the eighth member, however, he reaches out to Batman with a membership offer.