With the outbreak of World War I, Lord John aligned himself with German intelligence, offering his services as a weapon of terror. Adopting the codename “Baron Blood,” he concealed his identity behind a grotesque bat-like costume designed to instill fear in his victims. Acting as one of Germany’s most effective covert agents, Baron Blood carried out assassinations and attacks against key Allied figures, becoming a near-mythic threat during the war’s final months. During this time, he repeatedly clashed with the Freedom’s Five, a group of Allied super-agents that included his own brother Montgomery, secretly operating as the original Union Jack. Despite sustaining injuries—most notably from a silver blade wielded by Union Jack—Baron Blood managed to evade destruction and flee.

After World War I, Baron Blood devoted himself to the study of the occult, further deepening his knowledge of dark forces and vampiric lore. With the rise of Adolf Hitler and Nazi Germany, Blood once again saw an opportunity to align himself with a regime that mirrored his own ruthless ambitions. Rejoining German intelligence, he underwent a series of painful experimental procedures designed to grant him limited resistance to sunlight. While these treatments allowed him to function for brief periods in direct sunlight, they came at the cost of diminishing certain vampiric abilities, including his power of transformation.

Returning to England under the guise of “John Falsworth, Jr.,” supposedly his own descendant, Baron Blood reestablished himself at Falsworth Manor. Using elaborate disguises—including oversized dentures to conceal his partially retractable fangs—and claiming to suffer from a rare skin condition, he avoided suspicion while secretly resuming his predatory activities. During this period, he nearly succeeded in turning his niece Jacqueline into a vampire, an act that would have permanently bound her to his will.

Baron Blood’s renewed campaign of terror drew the attention of both Union Jack, who came out of retirement, and the Invaders, a team of Allied super heroes including Captain America. During a fierce confrontation, Blood’s identity was exposed, and he was impaled upon a stalagmite containing traces of silver, seemingly destroying him once more.

However, Baron Blood’s existence did not end there. He was later resurrected and joined the Super-Axis, a coalition of superhuman operatives aligned with the Axis powers. Though much of his activity during the latter part of World War II remains undocumented, he was ultimately destroyed again—this time by a wooden stake driven through his heart. Due to his aristocratic status, his remains were entombed within the Tower of London.

Years later, Dracula orchestrated Baron Blood’s return by manipulating a physician named Dr. Charles Cromwell into reviving him. Once restored, Blood murdered Cromwell and assumed his identity, relocating to the area surrounding Falsworth Manor. There, he resumed feeding in secret, sustaining himself by drawing small amounts of blood from unsuspecting patients while avoiding detection. Over time, however, his growing hunger drove him to resume outright killings, which local authorities attributed to a mysterious “slasher.”

The now elderly Lord Falsworth suspected that his brother had returned and summoned Captain America to investigate. As events unfolded, Blood—still disguised as Cromwell—positioned himself as his brother’s personal physician, intending to transform him into a vampire and condemn him to an eternity of frailty and suffering. However, his plans were uncovered when Kenneth Crichton discovered his true identity.

In the final confrontation, Captain America engaged Baron Blood in battle and ultimately destroyed him by severing his head with his shield. To ensure that he could never return, Blood’s head and body were burned separately, and the ashes scattered in different locations. The subsequent application of the Montesi Formula eradicated even these remains, permanently ending Baron Blood’s existence.

During World War II, experimental procedures conducted by German scientists allowed Baron Blood to withstand direct sunlight for brief periods, though this reduced certain vampiric abilities such as shape-shifting.

Limitations: Baron Blood shared the traditional weaknesses of vampires, including vulnerability to wooden stakes, silver, garlic, religious symbols, and decapitation. Direct sunlight would ultimately destroy him unless special protective measures were used.