In a war between Vampires and Werewolves, Vampires would win.

My first argument will be to show that vampires as a group would begin at a disadvantage, if only because of their almost unlimited number of weaknesses, which I shall expound on now. An inability to cross water - considering that an all out war would likely spread to several continents, vampires would be at a huge tactical advantage at the very least. It would be unreasonable to think that vampires could fight an effective war if they are limited to less than one-third of the planet for movement. As far as how werewolves might exploit this, fortifying strongholds with a moat would at least give them a safe haven to regroup, should the need arise. Also, they could all just clear out the vampires, one continent at a time, considering that the werewolves could use all of their numbers, concentrated on one continent, on the fractured populations of vampires, who would be unable to come to each other's aid if they happened to be separated by an ocean, or any body of water, for that matter. Extreme vulnerability to atoprophic objects - this is probably the largest disadvantage that the vampires would have, considering how common many of them are. The list includes, but is not limited to, seeds, knots, grains, garlic, thorns, roses, wooden stakes, and religious objects such as crucifixes. All it would take is for every werewolf to be "armed" with a few of these various items, which are common enough, and the vampires could barely stand a chance, at least head to head, with the werewolves. Hunger for blood - whereas werewolves just require massive amounts of meat, and are able to live on very little food for a relatively long time, vampires require blood, especially human blood, if they are to survive. And I think it is safe to assume shortly after the beginning of this war, the casualties to the human population would be significant - probably not to the point of extinction, but at least enough to put a strain on the food supply of the vampires. Also, the werewolves could, from a strategic standpoint, choose to deliberately kill off humans, which would be an easy way to "starve out" the vampires. Again, this could be done at least enough to put a dent in the vampire food supply. I will conclude this round by saying that, while vampires are essentially either undead or slightly mutated humans, and therefore mostly human, werewolves have all of the mental characteristics of humans, aside from an unquenchable lust for flesh, plus all of the hunting prowess of nature's ultimate killer, the wolf. To couple the intelligence and planning of a human with the killer instinct and hunting savvy of a wolf, is to create an unstoppable adversary, and to pit this killing machine against what is essentially a human that can turn into a bat (oooh, scary), and that has only one food source (blood) to sustain it - this would be a massacre, my friends, and one of epic proportions, at that. In the next round I will most likely expound on all of the attributes of werewolves that make them such an unstoppable force. Good luck to my opponent, who will now have to account for how such a weak, vulnerable creature (as I have just shown the vampire to be) can even hope to stand a chance against the mighty werewolf.