Bob Layton joins Michelinie and Simonson for the big reveal in Hercules Unbound 9 (Feb/March 1977).
While Hercules, Kevin and Jennifer are on the Isle of Mann, having discovered that David Rigg is controlling the computers battling Lady Agatha Simms, the woman herself is escalating the conflict, pulling the Enola Gay and its atomic payload into their time period.
Hercules and Kevin get away from David, but as usual Jennifer gets left behind. Though at least this time she is just separated from the others, and not held captive. Hercules and Kevin wonder how David could be Agatha's opponent when he only went missing a day earlier. In fact, David is being controlled by a computer program, which nonetheless manifests as a glowing body. This program ran as the opposing side to Agatha's wargame, and has gained sentience. It is also interested in upping the game. It also gains a nuke, and uses Rigg to fire it at Agatha Simms.
Jennifer gets some action, destroying whatever mechanisms she can. This does free Rigg from the computer, and eventually she manages to set the system on self destruct. Even so Rigg really does die this time.
She re-unites with Hercules and Kevin in time for them to flee the Isle of Mann before the whole thing gets destroyed.
To their surprise, Agatha Simms and her bunker are untouched. She explains that she sent the nuke fired at her back through time, to Greece in 1986. This makes Kevin break down completely. That was the time and place of the first explosion in what would become World War 3. So it was Simms and her computer program that actually started the war that would become the Great Disaster.