John was born in Ireland.

The evidence

• “P. 0. East Milton ; born in County Cavan, Ireland, in January, 1801 ; lived on a farm ; he was 'deprived of a liberal education, but he is a man of ability and strictly straightforward and honorable in all of his dealings ; h^ married in County Cavan, Ireland, in April 1843, Miss Bridget Masterson, born in the same county in 1819 ; they had six children, five living: John, born in Ireland, January, 1844; Michael, born in Ireland, September, 1845 ;”

  1879-history-of-rock-county/36-bios-harmony.md, PDF p. 890 / book p. 894

  Butterfield, C. W., et al. The History of Rock County, Wisconsin: its early settlement, growth, development, resources, etc. Chicago: Western Historical Company, 1879. Cornell University Library via the Internet Archive, archive.org/details/cu31924028871585.

  Grade A: Found on a page of one of our sources