Having inherited Venport Holdings from his father, Josef is responsible for the most ambitious expansions of the company's assets in history. After Emperor Jules Corrino had revoked Venhold's monopoly on Holtzman engines, allowing other shipping companies to benefit from instantaneous travel. However, Venhold still retained the monopoly on creating Navigators. Ambitious and ruthless, Josef despised competition, claiming companies such as Celestial Transport were cheap imitators, charging cheaper rates than Venhold but at the risk of the ship being destroyed while folding space. Being a pragmatist, Josef paid no heed to the Butlerian anti-technology movement, until their actions started affecting his profit margin. He especially hated them destroying any inert Thinking Machines ships found in deep space or in previously-unknown systems, believing that those ships should instead be refitted and added to the Venhold fleet.
After his grandfather Adrien Venport died during the attempt to become a Navigator like Norma Cenva, Norma became withdrawn and refused to get involved in the outside world. Somehow, Josef had managed to get her to open up and rekindle her interest in the future of humanity.
In order to further enhance his position, Josef married a Sisterhood of Rossak trainee named Cioba, finding her to be as shrewd at business as himself. Josef would often leave her in charge of Venhold's day-to-day activities, focusing on the bigger picture. It was at Cioba's insistence that he granted Reverend Mother Raquella Berto-Anirul and several other sisters sanctuary after Emperor Salvador Corrino had outlawed the Sisterhood of Rossak, re-settling them on Wallach IX.
Josef invested considerable resources into secretly sending people to be trained as mentats on Lampadas. One of these, Draigo Roget, became one of Gilbertus Albans's most prominent students. Along with his teacher, Draigo calculated the location of an abandoned Thinking Machine shipyard. Draigo told his employer Josef Venport of this, allowing Venhold to seize control of the shipyard from Arjen Gates, the president of Celestial Transport. Unfortunately, Josef's dreams of countless ships produced by the automated shipyard were obliterated along with the shipyard, which was attacked by Manford Torondo's Butlerians. Thousands of Venhold employees were killed by the Butlerians. Josef and Draigo only managed to escape when Norma Cenva sensed their peril and arrived aboard a spacefolder to save them.
Infuriated by the loss of the shipyard and personnel, Josef ordered all Venhold ships refitted with latest weapons and Holtzman shields, vowing to put a stop to the Butlerians.
Meanwhile, Josef continued to work on re-establishing his family's monopoly on foldspace travel by crushing the competition and using sabotage to present the other shippping companies, especially EsconTran, as having an atrocious safety record. To this end, he had Draigo recruit half-a-dozen young Freemen of Arrakis, who were suspected of sabotaging spice mining operations. Enticing them with the stories of worlds full of water (especially the oceans of Caladan), the Freemen, especially young Taref, agreed to work for Venport Holdings as saboteurs.
As the conflict between the Butlerians and VenHold escalates, both leaders put a price on one another's head. Josef sent Taref to Arrakis to recruit more Freemen. While Taref failed to convince anyone else in his sietch, when returning to Arrakis City he spotted Manford Torondo arriving to incite the populace. Taref used his Maula pistol to shoot the Butlerian leader in the head and escaped to return to Kolhar and report the successful assassination. Unbeknownst to Taref or Josef, Taref only killed Manford's body double. Manford headed to Salusa Secundus and demanded that Emperor Salvador imperialize all spice mining as a strategic resource in order to strip Josef Venport of his power. Salvador agreed and opted to personally travel to Arrakis aboard his barge to oversee the hand-over. While outwardly compliant with the Emperor, Josef resolved to assassinate the Emperor, so that his more reasonable brother Roderick, who has no love for Manford or his fanatics, ascended to the throne. He sent Taref aboard the Imperial barge to sabotage the navigation system of both the ship's Holtzmann engine and the old-fashioned FTL drive, so that the barge would be forever lost in interstellar space. Feeling guilt, Taref only completed part of the sabotage, forcing Josef to go with a backup plan. He lured Salvador aboard a spice harvester and paid the spotters to delay announcing wormsign until it was too late, himself escaping on a small flyer. However, just before a sandworm swallowed the harvester, one of Salvador's guards sent a message to the Imperial barge, announcing Josef's treasonous actions. Josef summoned the VenHold fleet to destroy the barge, but the crew managed to engage the Holtzmann engine. When the barge did not return to Salusa Secundus, Josef assumed that Taref's partial sabotage worked. After Roderick was crowned Emperor, Josef personally traveled with Norma Cenva to the capital world to congratulate him. However, just then, the barge managed to find its way back to Salusa Secundus and reported Josef's betrayal. The enraged Roderick ordered Josef arrested, but Norma Cenva used her mental abilities to fold space whisk both of them back to Kolhar.
At some point, Manford Torondo obtains a supply of forbidden atomics from a loyal Landsraad nobleman. He uses the weapons in a massed attack on Kolhar. Even the planet's considerable defenses are unable to protect it from a rain of atomic fire. Josef only manages to survive thanks to Norma Cenva's timely warning. Taking what remains of his fleet to Arrakis, Josef summons Roderick there and offers to make peace. Roderick agrees, on the condition that Venport attacks the Butlerian planet Lampadas, while the Emperor secretly sends a fleet of Imperial warships to attack both forces, when they are sufficiently weakened.
Upon arrival to Lampadas, Venport sends his cymeks down to the surface to wreak havoc, while his space forces engage the remaining Ballistae of the Butlerians. Despite the technological advantage, Venport's forces sustain heavy losses due to the Butlerians' suicide tactics, including ramming and firing lasguns at shields. Venport is forced to order his ships to lower their shields in order to keep them from being vaporized by the laser/shield interaction, while opening up the ships to direct fire. In the midst of the battle, the hidden Imperial fleet reveals itself and attacks both forces. Shocked at this betrayal, Venport orders his remaining ships to jump away to Denali , buying time for the jump by contacting Admiral Harte and threatening to end the life of the Emperor's sister Anna.
At Denali, Venport prepares his remaining defenses, knowing that the Emperor would find him sooner or later. Indeed, not long after the battle, a large Imperial armada, with Roderick himself in command, arrives to Denali. Venport hopes to once again use Anna Corrino as leverage, but Anna's suicide puts a stop to that plan. The Emperor's forces attack the remains of the VenHold fleet. However, the battle in space is stopped, when Norma Cenva appears on the bridge of the Imperial flagship and negotiates with Roderick on behalf of all Navigators. Roderick agrees to spare all current and future Navigators in exchange for Norma Cenva removing all VenHold ships from Denali orbit, leaving the planet open to attack.
Feeling betrayed by his great-grandmother, Venport locks himself in his office, while an hours-long battle rages on the poisoned surface of the planet. Countless Imperial troops are landing and battling his remaining cymeks and reactivated combat meks. Eventually, the battle is won, and Venport contemplates suicide in lieu of a public execution. However, just then, Norma Cenva appears in his office and offers him a last chance to survive by entering her spice tank and initiating the process of becoming a Navigator, which would force Roderick to spare him as per their agreement. Venport agrees, and Roderick eventually accepts this fate for his enemy.