The 1st Supernatural War took place some time after Lucifer was casted out of Heaven. He created his realm that he called Hell where he could gather his forces with interfering with life on Earth. Michael created the realm of Paradise where his forces would gather to beat back Lucifer's army whenever he attempted to force his way back into Heaven, the home realm of God.
Lucifer and his army of Dark Angels were defeated and were forced to retreat back to Hell.
Lucifer's 1st Dark Angel and General Ultimor was infuriated with Lucifer's decision to retreat and was killed by Lucifer after openly challenging him in front of the other dark angels.
Seeing another opportunity to torture Lucifer even further God secretly resurrected Ultimor and subsequently created the first vampire. An immortal being that required the blood of humans to survive and gain strength.