Max,
OK, that rules out marriage records in Baddeckenstedt or Berlin. Still it may make sense to check the church book of Baddeckenstedt. May be Julius B. was married before to somebody else, figures as godfather or was actually born there. I can easily believe there are no civil records prior to 1875 but for sure there are church books, a have a look here:
It states that church books for B. exist for the years 1656 - 1875 (as Microfiches) in the Archive at Wolfenbuettel. It can't hurt to contact the city of B. either, may be they have some kind of archive nevertheless: http://www.baddeckenstedt.de/.
Regards,
Nils