John Bechtel was born near Mainz, Germany, in 1822. While a young man, he emigrated to Milwaukee, where he became the proprietor of the Mansion House. In 1851 he married Mary Siebert, also a German immigrant; they had five daughters and one son. The Bechtels espoused the Roman Catholic faith with pious fervor. At least three of their daughters attended the Day School at St. Mary's Institute in Milwaukee, there receiving lessons in English and German as part of their academic program.
Family ties with relatives in Germany and in Illinois remained strong. One young man, either Bechtel's nephew or cousin, was sent from Germany to settle in Milwaukee; when he returned to his homeland in poor physical and economic condition, the family heatedly accused Bechtel of having failed in his duties as a kinsman. The Wollard family of Fayette County, Illinois, were also close relatives.
