The First Leviathan War was the a conflict between Dick's Leviathan forces against the leader's Leviathan forces.
Battle[]
God creates the Leviathans, but they begin feasting on each other ravenously, devouring angels and other creatures. In a contest of survival of the fittest, Dick kills high ranking Leviathans and the leader, becoming the alpha predator. This entertains Death.
Aftermath[]
God is concerned for all other life forms, so He locks them in Purgatory, due to their uncontrolable hunger.