My William Chamberlain was married in 1883 in Anoka, Minnesota, to Elizabeth Milton. The information available on his marriage has no birthplace listed. His obit shows his birthplace as "Bengal" Maine - I think that's probably Bangor, Maine, as I can't find any trace of a town named Bengal, and other records say Bangor. There is nothing on his parents in either his obit or his death certificate, and none of his other descendants have any information either.
There are two William Chamberlains that are the right age in the 1870 Census - William, the son of Aaron Chamberlain of Castine, and William, who is living with the Whitmore family in Hudson. In over 30 years of trying, I haven't been able to document which one is my William.
For a variety of reasons, I think it's more likely to be the one living in Hudson, but I can't prove it. The family trees I've been able to find on Ancestry all show Aaron's son William with a birth year of 1861, but no death date. So I thought I'd see if I could find out what happened to him - and I'm hoping his father's will or probate record says something useful.