The man known as the Vulture was a Nazi scientist who invented a drug that increased the strength of a man 20 fold and allowed them to fly. The process caused his skin to turn green. Within the United States, he used his drug (which required 24 hour re-injections otherwise those on the drug died) to create an army of slaves he dubbed the Batmen.
In the fall of 1943, the Vulture and his Batmen began a campaign of terror, capturing public figures who were helping the war effort within the United States and carrying out acts of sabotage to undermine the defense within the United States.
His activities attracted the attention of Captain America and his partner Bucky. After foiling the Vulture's attempts to capture various figures and carrying out acts of sabotage, they caught one of his Batmen and tracked the Vulture to his hideout. They were then captured by the Batmen and brought to the "Aerie" - the Vulture's secret lab in a mountain that could not be scaled by normal men.
There, the Vulture offered to let Captain America free and give him untold riches if the hero would promise to not interfere in his plots. Captain America refused and was locked in a cage along with Bucky. Captain America broke free and defeated the Vulture and using the scientist's own serum on himself and the Vulture's other captives escaped the Aerie. Before leaving, Captain America destroyed all means of making more of the serum and left the Vulture and his Batmen to die when the serum wore off in 24 hours.
Powers and Abilities
When exposed to her serum, the Vulture had the strength of 20 men and was able to fly under his own power.
Apparently, the Vulture required new injections of his drug every 24 hours or he would die.
The Vulture wore a pair of synthetic wings to assist in his ability to fly.
There are some inconsistencies in the Vulture's story regarding his serum that allowed people to fly. Firstly, it does not make sense that the strength of 20 men would allow one to fly under their own weight, as there are other beings in the known universe who have this much strength but are incapable of flying. It stands to reason that perhaps an additional effect of the serum was levitation, hence explaining the need for synthetic wings.
The other inconsistency is regarding the necessity of re-injections of the formula every 24 hours or risk death. This is evident as Captain America, Bucky, and the Vulture's other prisoners used the drug to fly out of the Vulture's Aerie with no regard for its side effects and have not appeared to have any ill effects as a result. Also, unlike others who were exposed to the drug, their skin did not change color or go through any other physical changes as a result of their exposure. It is possible that while the drug the Vulture injected his Batmen with was lethal if they were not given a new dose in 24 hours, the version that the Vulture used on himself provided no ill effects, hence why Captain America and the others were able to use it with no ill effect. This would suggest that while the other Batmen likely died once the 24 hours were up, the Vulture either survived and managed to escape or died a more lingering death due to starvation while trapped atop his Aerie.
Der Geier is German for Vulture.