Israeli defense company Rafael will bring the technology. Reports say the factory could build Iron Dome launchers, generators, military vehicles and other equipment for Germany and Europe. The interceptor missiles will not be produced there.
The 125-year-old factory currently builds Volkswagen and Porsche models, including the Cayman and Boxster.
Volkswagen planned to end production because of weak demand, but the new deal could preserve about 1,400 of its 1,800 jobs.
Aurelius would become the majority owner. Qatar, a major Volkswagen shareholder, reportedly opposed the original direct partnership with Rafael. The new ownership structure allowed the project to move forward. The purchase price was not disclosed, and final approvals are still required.