Darth Vader’s failures were usually connected to Jedi who escaped him, Rebels who survived his attacks or his inability to capture Luke Skywalker.
But one of his most horrifying failures in Legends began when the Empire tried to transform an ancient Sith plague into a biological weapon.
The virus later known as Blackwing could kill its victims, reanimate their bodies and connect the infected through a growing collective intelligence. Vader believed Imperial scientists could study and control it.
Instead, the project destroyed an Imperial Star Destroyer, spread to a prison barge and created the zombie outbreak at the center of the novel Death Troopers.
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The Plague Began Thousands of Years Before Vader
The origin of the virus is revealed in Joe Schreiber’s Legends novel Red Harvest, which takes place during the Old Republic era.
At a Sith academy on Odacer-Faustin, Darth Scabrous became obsessed with overcoming death. Using Sith alchemy and a rare Force-sensitive orchid, he attempted to create a formula that could grant immortality.
The experiment did not work as intended.
Instead of preserving life, it created a plague that killed its victims and reanimated their bodies. The infection spread through the academy, transforming Sith students, servants and other inhabitants into violent undead creatures.
That ancient outbreak established the origin of the horror later seen in Death Troopers.
However, Vader’s involvement is not revealed directly in either novel. Red Harvest explains the plague’s Sith origin, while Death Troopers shows the result of an Imperial biological experiment centuries later.
Vader’s personal connection comes from additional Legends material.
According to that expanded history, Vader commissioned Imperial scientists to recreate and weaponize the ancient plague under Imperial bioweapons Project I71A, also known as Blackwing. The objective was not simply to study the dead.
The Empire wanted a weapon that could be released against enemy populations, kill them quickly and potentially transform the victims into creatures that would continue attacking anyone left alive.
Vader was therefore not dealing with a newly discovered Imperial disease. He was deliberately reviving a Sith-created horror that had already destroyed nearly everyone exposed to it.
The Vector Became the Project’s First Victim
In 1 BBY, an Imperial Star Destroyer later identified in Legends as the Vector was ordered to retrieve Blackwing-related materials from Meglumine.
The ship was supposed to transport them to an Imperial testing facility on Khonji Seven, where the project could continue under controlled conditions. It never arrived.
During the journey, one of the containment tanks ruptured. The infection spread through the vessel before the crew could stop it.
Imperial personnel became sick, died and then began moving again.
The infected were not simply mindless zombies. Although they initially behaved like feral creatures, the plague connected them through a form of collective intelligence. Information learned by one infected host could be shared with the others, allowing them to coordinate their movements and adapt to resistance.
That made Blackwing far more dangerous than the Empire had expected.
It was not a weapon that could simply be released and forgotten. The infection could learn through its victims and seek new ways to spread itself.
The Vector was overwhelmed and left drifting through space, filled with the reanimated remains of its own crew.
Instead of delivering a controllable biological weapon to the Empire, Vader’s project had destroyed the Imperial personnel responsible for transporting it.
But the disaster did not end with the loss of one Star Destroyer.
The Purge Carried the Infection Aboard
Several weeks later, the Imperial prison barge Purge experienced mechanical problems while transporting hundreds of prisoners.
Its crew discovered the abandoned Star Destroyer and believed it might contain the equipment needed to repair their ship.
A boarding party entered the derelict vessel.
They found almost no living crew, but they did recover supplies and replacement parts. By the time they returned to the Purge, some members of the team were already infected.
This is where the events of Death Troopers begin.
The sickness spread rapidly through the prison barge. Guards, officers and prisoners developed severe symptoms before dying and returning as part of the infected collective. The Vector had become a trap.
Its original crew had been destroyed by Vader’s failed weapons project, and now the abandoned vessel was drawing new victims aboard and carrying the infection into another ship.
Only a small number of people escaped the Purge, including Han Solo and Chewbacca, who were prisoners aboard the barge at the time.
Vader had wanted a plague that the Empire could direct toward its enemies. Instead, Blackwing consumed Imperial soldiers, prison personnel and civilians without distinguishing between them.
The project never reached the battlefield for which it had supposedly been designed.
It attacked the Empire first.
The Empire Still Refused to Abandon Blackwing
The destruction of the Vector and the outbreak aboard the Purge should have ended Project I71A. It did not.
Later Legends material connected to Star Wars Galaxies revealed that Imperial research into Blackwing continued at a secret research and prison facility on Dathomir.
The Empire relocated the project instead of destroying it.
That decision led to additional outbreaks as Imperial scientists continued experimenting with the plague and the creatures it produced. Even after Blackwing had wiped out ships and personnel, the Empire still believed it could eventually control the infection.
That makes Vader’s failure larger than one containment breach.
His attempt to weaponize an ancient Sith plague kept the disease alive thousands of years after the original outbreak described in Red Harvest. The Vector disaster did not destroy Blackwing. It allowed the virus to spread to the Purge, while Imperial research later carried it to Dathomir.
Vader wanted to turn death itself into another weapon of the Empire.
Instead, he helped revive something that could not recognize allies, follow orders or remain contained. The result was not an army of obedient undead soldiers.
It was a plague that destroyed the people trying to control it and waited inside a drifting Star Destroyer for its next victims.