Fuzzy Beginnings

Under our very noses, for centuries unnoticed by human-kind, a war has been brewing between two horrific groups of people. Of course, I'm referring to the epic battle between Werewolves (Lycanthropes) and Vampires.

Something like this, right?

Most pieces of modern fiction that depict this war ask the audience to chose one side or another, either by present one as the 'heroes' and the other as the antagonist, or by giving a player the option to choose a side (as in games). After much research and deliberation, I decided of the two groups, I much more of a werewolf fan than a vampire fan, for reasons I'll explain below, but first I must address one important question; why is there even a war to begin with?