You want to have a war that can move continents? Sure, it is easy. All you need is a bio-weapon and some cryogenic suspension modules with faulty wake up circuits.

The continents move on their own. They just do it very slowly.

You want to have a war that can move continents? Sure, it is easy. All you need is a bio-weapon and some cryogenic suspension modules with faulty wake up circuits.

First, use the bio-weapon to wipe out the majority of the combatants on both sides. This isn't really necessary, but it cuts down on the number of hibernation modules you will need.

Then, with the plague ravaging the planet and endangering extinction, have the survivors retreat into the hibernation modules to let the plague burn itself out. Set the timers for a hundred years, to give the corpses time to rot away, but have those timer's fail.

Keep the survivor-sickles on ice for a hundred-million years or so. During this deep time, the continents will move on their own. All signs of the previous civilization will also erode away, giving you a virgin, unrecognizable world for the survivors to wake into.