Hi,
I understand each church pastor had to submit an annual list of males old enough to be conscripted into the military, and in turn the military publicised the names of males who did not report for duty when instructed to do so.
Where would I look to find a list containing Conrad Ehlers who was born about 1829-1831 in the Salzgitter area and left home when he was 18 years old because he did not relish going into the navy? This was a very popular name and I have seen already that one migrated to the USA with his family - I'm not looking for him 
I presume no newspapers would have survived but possibly there could be a film?
Was it easy to get in and out of Hannover at the time? He was obviously in contact with his family as years later he married a local Salzgitter girl and English census showed he had other relatives (the Dormann's, etc) staying with him at various times.
Hi Rena,
The birth of Conrad Ehlers still remains a mystery to you. I don't
have much to offer, but I thought I'd tell you that it must be the case that
people got on immigration ships without getting permission to emigrate.
None of my relatives from Hannover are on the emigration archives! The
family lore has it that my great-grandfather left Hannover to avoid the
military. I have not found him on any ship list either. I don't know if they
used bribery or whether they had other ways of getting on ships without the
proper papers. But I do believe it happened.
I would guess that you would have looked at the shiplists from Hamburg
to England. The Hamburg ships often stopped in Britain.
There are some listings for various films on the LDS site if you
search for Salzgitter in Place, Keyword or Subject. Perhaps, you may find
something by using Hannover (in Place) - there are a lot of military records
there.
You are such a seasoned researcher and I would guess that you have
already looked in those places I suggested. I wish you luck!
Barbara