(covers information from several alternate timelines)
Vosk was the leader of the Na'kuhl, a faction in the Temporal Cold War. Originating from the 29th century, Vosk was strongly opposed to the Temporal Accord, believing it was his right to use time travel for the benefit of his race.
Vosk was perceived as being the most dangerous participant in the Temporal Cold War by Daniels' faction, and he was once very nearly captured by them. However, Vosk developed a form of stealth time travel, allowing the Na'kuhl to escape to Earth in the year 1944 in a timeline which had been severely altered by multiple temporal incursions by various Cold War factions. In this timeline, the Nazis had launched a successful invasion of the American east coast and were steadily moving forward in their efforts to conquer the world. Vosk formed an alliance with the Nazis, promising to provide them with highly-advanced technology with which to wage their war in exchange for materials and resources with which to build a temporal conduit to return to the future.
Vosk was often at odds with the German generalmajor serving as the liaison between the Nazi party and Vosk's people, who grew impatient at Vosk's stalling. When Vosk and his people were preparing to return to their own time, the treacherous Na'kuhl leader ended his alliance with the Nazis by killing the generalmajor.
The Na'kuhl eventually completed the conduit and used it to launch an attack on Daniels' faction, igniting the Cold War into an all out conflict and resulting in the very alternate timeline to which they had escaped. In a last-ditch effort to restore the timeline, Daniels transported Captain Archer and Enterprise NX-01 from 2154 to 1944 so they could stop Vosk. The crew of Enterprise was eventually successful, destroying the temporal conduit moments before Vosk could enter it. This had the effect of resetting the timeline and bringing the Temporal Cold War to an end. (ENT: "Storm Front", "Storm Front, Part II")