Rinderpest (a cattle disease) and Smallpox are the only two diseases ever successfully eradicated. The smallpox vaccine was the first vaccine ever invented and it took until 1980, about 180 years later, to eradicate the disease entirely. It pretty much is an unceasing war, though Guinea worm and polio are also relatively close to being eradicated. But if you stop fighting them, they'll just spread again.