Hellsing: Ultimate OVA

Alucard has a dream about his defeat at the hands of Abraham Van Hellsing, while Sir Integra holds a Round Table conference to report her findings regarding the current wave of vampire attacks, vampire brothers Jan and Luke Valentine launch a covert sneak attack on the Hellsing compound with the help of a ghoul army outfitted with military gear and small arms. Almost all of the Hellsing soldiers are killed in the process and turned into ghouls before Alucard, Seras and Walter C. Dornez (who shows why he was once known as the "Angel of Death") are able to turn the tide. Jan reveals the name of the group responsible for the attack as Millennium. Integra hints to Walter that surviving Nazi officials could have been responsible for the attack.