"We are on a mission from God." Hellsing's Motto. The Organization of the Hellsing family and it's purpose is to hunt down and kill the supernatural foes who threaten England
Great Britain, in the Hellsing Universe, despite strong appearances to the contrary, is still essentially ruled by a monarchy heavily supported by a group of twelve aristocrats, the Convention of Twelve, each commanding a section of the main power structure in the staunchly Protestant country. These seats are hereditary, and one of them is reserved for the heir of the Van Helsing family, who have taken the name Hellsing. The Hellsing Family oversees matters concerning supernatural threats and their neutralization. Its founder, Abraham Van Helsing himself, and a group of adventurers, captured and subjugated the most powerful of all vampires, the ancient voivode of Wallachia, Dracula himself.
This powerful undead was experimented upon, its powers enhanced to abominable levels, and used as a weapon to destroy Great Britain's supernatural enemies. It was renamed Alucard,and bonded to the Van Helsing bloodline to obey as their servant. The first recorded usage of this living weapon came in WWII, when by orders of the then holder of the Hellsing title and manor, Sir Arthur Hellsing, Alucard was deployed along with fellow Hellsing servant Walter C. Dornez, to destroy the Nazi Order 666 camp and experiments, which dabbled in the creation of artificial vampires through different forms of surgery and serums. This mission would be successful, though with unforeseeable consequences for the Organization and London itself. This was mainly due to the strange survival of the three main Order 666 members, the Major, the Doctor and the Captain, who would move on to South America with great amounts of the stolen Nazi wealth and many followers, eventually founding the Millennium Group.
Alucard would be later sealed under Sir Arthur's orders, who believed he was "too strong a draught to be used more than the occasional medicine"; Walter would continue to serve the Hellsings as their butler and personal trashman. Upon Arthur's death, his brother, Richard , hoped to be named heir to the title and manor, but Arthur had unexpectedly named his own young daughter, Integra, as the successor. Enraged by this, Richard attempted to kill the girl, but, acting upon her father's orders upon emergency states, she snuck to the manor's dark cellars, and found the cell where the dessicated vampire still rested. Richard found her there and shot her, non-fatally. While he was moving in for the kill, the girl's blood powered up the vampire's corpse, and acting upon the commands to protect its master, it killed the men accompanying Richard, defended the young Integra, and allowed to execute her traitorous uncle.
Eventually, Alucard returned to prominency upon the rise of artificial vampires on Great Britain; as the greatest anti-vampire agent, he was often used to deal with the threats. One night in 1998, Alucard sired a fledging, a former policewoman named Seras Victoria, who had nearly died in the struggle against a vampire priest. The young Draculina was forced to incorporate into the organization and her status was reported as KIA. Alucard was forced to abide for his decision and guide her in the ways of vampirism. He was then drawn into a confrontation against the Hellsing Organization's Catholic opposite, the Vatican's own Section XIII : Iscariot, and their own ace card: the Paladin Alexander Anderson, upon attacking a target in Badrick, Ireland.
Shortly after, a strike team composed of two artificial vampires ( Jan and Luke Valentine) and a large assembly or armored ghouls, soulless vampiric puppets, struck at the Organization's HQ during a Convention of Twelve meeting, and decimated the organization's ranks until only four active operatives survived: Walter, Integra, Alucard and Seras. Upon the destruction of the invading forces, the defenders heard from Jan Valentine's lips a single word, their sole lead on their attackers: Millennium. In seeking information, Iscariot, through means of its leader, Bishop Enrico Maxwell, offered Hellsing a dossier containing information of the Millennium Group to pay the blood debt incurred in the Ireland incident, though Integra did not like Iscariot meddling in Great Britain and liked Maxwell even less because of his own chauvinist, arrogant and fanatical views. Because of the devastating attack against Hellsing's ranks, Dornez hired a huge force of mercenaries known as the Wild Geese to serve as their standing army, with Commander Pip Bernadotte as direct leader under Integra's orders.
Hellsing then would move on against Millennium, seeking them in South America, starting on Rio de Janeiro. A Millennium operative, also an artificial vampire ( Tubalcain Alhambra) attacked them; he was promptly killed after a spectacular declaration of war against Millennium. While at a summit between the Convention, Hellsing and Iscariot, a Millennium envoy ( Schrodinger) reached past security and delivered a TV from the Major, who responded to the declaration of war and challenged all present to stop him. Not much later, another Millennium operative, a sharpshooter (Rip Van Winkle) moved in and captured a VTOL carrier near the English coast, the Eagle, surrendered by traitorous Englishmen, similarly vampirized.
Rip Van Winkle defended the ship against external attacks, but was ill-equipped to handle a kamikaze attack by Alucard, who reclaimed the warship at the cost of wrecking it. As Alucard could not cross the ocean without external means of locomotion, Millennium was poised for an attack on English soil. Thus, Hellsing lost its ace card, allowing Millennium to brutally level London with a barrage of missiles when the military and navy's communications were jammed and the Nazi zeppelins loomed over the city. Integra was forced to move through the destroyed city after leaving a defense committee, and Walter left her to battle the Captain; she would find Alexander Anderson and join his Iscariot batallion, as the armies of Christianity moved for another Crusade. Hellsing, the only local agency trained to deal with the threat, sealed itself and barricaded within the manor. Another Millennium operative ( Zorin Blitz) attacked the manor with a detachment of Millennium shocktroopers, but the zeppelin she commanded and the missiles it carried were destroyed by heavy gunfire by Seras' Harkonnen II Field Dominance Weapons System, leaving Zorin with no option but to command ground invasion of the manor, aided by her illusory powers. There, because of her sadism and hubris, she committed several critical mistakes, including leaving Seras alive after a brutal beating, giving her the chance to finally accept her heritage (she had previously refused to drink blood) and drain the recently deceased Captain Bernadotte, absorbing his soul and becoming a full vampire.
With regenerated strength, Seras all but shredded Zorin's men, saving the few Geese still standing, and then moved in to execute Blitz. She then used her new powers to manifest a shadow-matter wing and flew to downtown London to defend Integra from the Iscariot priests she had been forced to travel with for protection, who were ready to act upon Maxwell's orders and apprehend her, at the immense fury of Paladin Anderson, who objected such a measure, knowing full well Maxwell intended to settle a silly vendetta at the cost of the lives of countless Englishmen. Alucard, meanwhile, had manifested shadow-matter sails for the Eagle, enveloped the warship in a bank of mist and crashed right into the battle of the Christian armies against Millennium forces. Alucard then manifested the entirety of all the familiars he had ever absorbed, adding countless warriors to the fight for England; these were considered the Army of Hellsing, along with Integra and Seras. Alucard would then confront in sucession a divinely empowered form of Anderson and a vampirized Walter; the main result of these encointers was the virtual destruction of Iscariot. Meanwhile, Seras and Integra fought the last of the Major's forces and ultimately destroyed the Millennium threat by killing the remaining vampire Nazis and the Captain.
On his side, Alucard defeated Walter and started drinking the blood from all of London. This was "poisoned" with Schrodinger's blood, making him fade out of existence due to the nature of the powers of the catboy. The last to die were Walter and the Doctor, leaving the Hellsing Organization down to a few Geese guarding the ruins of the manor, Seras and Integra. Thirty years later, Integra would remark she believed the institution would die with her, shortly before Alucard's return.