Part 2/10:
Contrary to popular belief, Sauron did not require the One Ring to reconstruct his physical body after it was destroyed. The process of physical regeneration was laborious and could take upwards of a millennium. To put this in perspective, a thousand years is nearly twice the duration of the First Age. After each defeat, Sauron's spirit would vanish, leading many to assume he had been defeated for good. In essence, he would fade into myth, becoming a forgotten enemy.