This war was instigated and triggered by the Blue Demon Clan and the Central Nations in order gain profit from the war effort from both sides.
During the WarEdit
At the time when the war began, many human nations were united under a single banner, so did the demon clans and fought countless battles that took many lives and destroyed lands.
Eventually, the human expedition was sent forth into the Demon realm where they successfully captured Gate City after a long siege and established it as humanity's stronghold. However the demons had it even by capturing Aurora Island, the only human territory near the Demon realm.
Through it, the demon forces attacked the Southern Nations and fought numerous skirmishes with the human troops of those kingdoms, thus chaos ensued.