Second Angelic War

The Second Angelic War, also called the Watcher Rebellion, was a revolt against Yahweh by Angels called the Watchers and their half-human offspring known as the Nephilim. The rebel angels were led by Samyaza and Azazel, the loyalist angels were once again led by Michael.

Aftermath and Consequences
Following their defeat the Watchers were cast into the Outer Darkness to be imprisoned there until Armageddon. Azazel was imprisoned in an area of the Outer Darkness called Dudael.

After the war was over, Yahweh unleashed the flood killing all the remaining Nephilim. The spirits of the Nephilim killed during this floor became demons.

Future angels would continue to lust after humans and produce Nephilim, which is what accounts for the existence of Giants later on in the Bible such as Goliath.