Battle of London Arc

The Battle of London is the war created by the Major against Hellsing. In the OVA series, this event debuted in Volume/OVA 5. Officially, this battle is called Operation Sea Lion 2 (Unternehmen Seelöwe Zwei)

Attack on London/Arrival of the Papel Knights
This event starts off when the Last Battalion's fleet of three Zeppelins in the skies above London. After launching a devastating salvo of V1 rockets that cripples the infrastructure of London and kills many civilians, the soldiers of Millennium are launched from the airships and land in the city blow London and try to capture Integra Hellsing, killing everyone they find en route to their objective. Then Iscariot appears saving and capturing her from Millennium. Enrico Maxwell is promoted to Archbishop and leaves with his army of Papel Knights.

W.Geese and Seras v. Zorin Blitz
Zorin Blitz is sent by the Major to kill Seras and her forces slaughter the Wild Geese. Seras easily kills all of Zorin's soldiers but Seras herself is caught in Zorin's illusion and she is heavily wounded by Zorin and her scythe. Pip saves Seras, but is killed by Zorin. Seras bites Pip and sucks his blood to become a True Vampire. terrifying and wiping out Zorin and her forces.

Maxwell's Betrayal/Alucard's Level Zero
She leaves to London where the battle takes place and Maxwell uses his army to kill Millennium forces and British civilians. Anderson and Integra are outraged by Maxwell's betrayal and The major had The Doctor turn the Hellsing butler Walter C. Dornez into a Vampire. Integra was about to be captured by Iscariot forces until Seras comes in and Alucard returns to London with the eagle,he jumps from the building and joins the fight along with the other trump cards Alexander Anderson and The Captain. He is in Level Zero and summon his familiars easily wiped out all of the Vatican forces and some of Millennium's.

Alucard and Anderson Clash
After Maxwell dies, Anderson goes off to fight Alucard and the two clash. Anderson is having trouble but is saved by the remaining Iscariot forces and after getting past some ghouls Anderson goes up to face Alucard.

Anderson uses the Nail of Helena to become a monster against Alucard. Anderson used his new powers to burn Alucard and his familiars on fire and Seras intervenes awaking her master from the monstrous Anderson. Alucard, now awakened, transforms into his Cromwell form and launches his final attack against Anderson. While Anderson uses his thorns to burn Alucard and his familiars, Alucard pierces Anderson's chest and removes his heart and the nail. After crushing both Anderson's heart and the attached nail, Alucard mourns Anderson's transformation saying that it reminds of himself when it happened to him 500 years ago Anderson gave him a words of Pity before he dies.

Walter, the Traitor
Walter, now a vampire, jumps from the air and crushes the remains of Anderson. Walter mocks Anderson saying that trash should not be mourned. Yumie, angered by Walter's disrespect, tries to kill Walter but is killed instead. Heinkel, who tries to save her, is shot in the cheek by the Captain. Walter challenges Alucard to a duel While Integra and Seras go after the Major. Walter and Alucard begin their duel walter seems to have the upper hand but fails with his transformation and Alucard now has the advantage.

Integra and Seras vs. The Captain and Major
Integra and Seras are killing all of Millennium's forces as The Captain approaches. Integra leaves Seras to fight The Werewolf while she goes after the Major. Seras and The Captain begin their duel and Alucard (in his female form) begins to absorb the blood of everyone who died in London. The Captain becomes his Werewolf form and Seras is easily getting beaten. Pip who communicates with her gets back on her feet and fights back. Seras and Captain gave fatal blows to each other but Pip as Seras's familiar uses a silver tooth to kill the Werewolf.

Integra Finishes the Major/Alucard is Put Down
After killing the Letzte Battalion forces manning the zeppelin, Integra arrived in the control room where the Major was waiting. Protected behind a wall of bulletproof glass, the Major told Integra that she was just in time to watch his final triumph over Alucard, who had just defeated Walter. As the vampire began absorbing all the blood in London, the Major patiently watched and waited, mocking Walter's last desperate attempt to kill Alucard. Musing that his nemesis had now gained millions of lives by absorbing blood, the Major explained to the distraught Walter that he was just another life sacrificed for his grand plan of destroying Alucard for good. When Alucard finally finished absorbing the blood, the Major gleefully announced that he had won - moments later, Alucard began to disappear. Integra demanded to know what was happening, and the Major was more than happy to explain: Schrödinger had killed himself and fallen into the rivers of blood, allowing Alucard to absorb him and gain the power of "the self-observing Schrödinger's Cat". However, Schrödinger's powers relied on his ability to perceive himself as an individual; since Alucard had millions of souls within himself, he was unable to control his newly-gained powers. Before Integra and the Major's eyes, Alucard vanished into thin air as he became "a collection of imaginary numbers", neither alive nor dead.

With Alucard gone, his army annihilated, and the Deus Ex Machina falling apart around him, the Major calmly faced Integra Hellsing and challenged her to kill him, stating that she was destined to be his slayer as he was Alucard's. After killing the Captain, Seras joined Integra and attacked the Major with her Harkonnen cannon, but the powerful shots barely cracked the glass wall. The Major wryly lamented that the Doctor had done too good of a job, but became elated when Seras pulled an 88 mm flak cannon from the armory beneath them. This enormous gun proved strong enough to shatter the shield, hit the Major, and punch through the wall of the zeppelin in the process.

As the smoke cleared, the Major lay on the ground with most of his left side blown off, revealing his cyborg nature. Integra wondered if this meant he was a monster, but the Major insisted that he was still a human because he had retained his own will and mind - he claimed that his ability to defeat Alucard was proof of his humanity. Drawing a small pistol from his coat, he again challenged Integra, asking her to "make war" with him. He repeatedly fired at his advancing foe without success, but finally managed to shoot her in the left eye as she shot him in the forehead. Despite this, the Major died with a smile, happy that he had finally managed to shoot something. As the machinery sustaining his life ground to a halt, he gloated to Integra that he had achieved everything he had set out to do; he had finished his grand war and destroyed Alucard. Integra retorted that Alucard would return one day, as he refused to die at the hands of anything but a human - and for all his claims to the contrary, the Major was still a monster.

Aftermath
The battle was over and, at the end of it, Millennium goals proved to be a fool's dream as none of the members survive. In addition while their leader, The Major, died without regrets, future developments would prove that he and his followers had ultimately failed at all they set out to accomplish. Far from being the seed of a world-consuming war, Millennium's attack on London was eventually classified as no more than a terrorist incident ("The Zeppelin Affair"). The city was rebuilt, and while both Hellsing and Iscariot were badly crippled they survived as well and would go on to regroup and gradually restoring their strength. Even the Major's plan to defeat Alucard eventually proved futile - thirty years after his apparent "death", Alucard managed to return, having gained control of Schrödinger's powers by destroying all of the other souls within himself. For all they sacrificed, Millennium's grand plan to kill Alucard only succeeded him stronger than ever.

Survivors

 * Seras Victoria
 * Heinkel Wolfe
 * Integra Hellsing
 * Few Wild Geese Mercenary
 * Survived England citizen
 * Survived England Police and Millitary Force

Killed in the Conflict

 * The Major
 * The Doctor
 * The Captain
 * Walter C. Dornez
 * Enrico Maxwell
 * Alexander Anderson
 * Yumie Takagi
 * Pip Bernadotte (later returned as Seras' familiar)
 * Schrödinger (absorbed by Alucard)
 * Alucard
 * Sir Shelby M. Penwood
 * Approximately 3 million London civilians
 * Thousands of British soldiers, police officers, army officers, etc
 * Vatican Army and Swiss Mercenaries
 * Millennium Vampire Army
 * Alucard's ghouls
 * Majority of the Wild Geese Mercenary Company

Status Unknown

 * Renaldo
 * Sir Hugh Irons
 * Rob Walsh

Trivia

 * Its unknown how long it took for London to resume functioning as a normal city; with a large chunk of the population dead.