Farmer-painter John O. Kroehnke was born in Schleswig-Holstein on September 2, 1810. Because the only information about Kroehnke comes from the four diaries in the collection, which begin with the year 1848, very little is known about the first 38 years of his life. Indirect references suggest that he may have had a background as a merchant or a seaman, and he appears to have been more affluent than the people with whom he immigrated. It is also known that he married about 1832 (although his wife's name is never mentioned in the diaries) and that he had four children by his first wife. The diaries also fail to indicate if the political motivation that lay behind the immigrant wave of 1848 also prompted Kroehnke's departure. It is unlikely that politics was the determining factor, for, as the diaries make clear, after 1848 economics rather than politics was his primary concern.
Kroehnke departed from the city of Marne in March 1848 and arrived in New York City on May 11. From there he arranged transportation via the Erie Canal and Great Lakes steamer to Sheboygan, Wisconsin. Soon after his arrival he filed on 360 acres near Lake Winnebago (Calumet City). Kroehnke remained on this farm at least until 1850. The next ten years are undocumented by diaries, and in 1861 when the coverage resumed he was a painter living in Sheboygan. Prior to this move Kroehnke's first wife died. In Sheboygan he married his second wife, Gretchen, and fathered six more children, of whom four survived to adulthood.
The years 1866 to 1870 are similarly undocumented in the collection. The year 1871, however, found him returned to the New Holstein area where he continued to work as a painter and settled on a 120-acre farm. Information about his life is also missing for the period 1876-1881. When the coverage resumed in 1881 he had become too old to maintain steady employment, although he continued to pursue his interest in painting and music. He appears to have lived off interest made from making private loans. The date of John Kroehnke's death is unknown.
