Common ancestor to hundreds of families in the U.S., Friedrich married Wilhelmina Hofheinz on Feb. 3, 1853. He emigrated to the United States from Spöck, Karlsruhe (in the Grand Duchy of Baden, of the German Confederation) with his sister Christine (Hartmann) Ernst and her family in 1868, following his younger brother Ludwig Theobald Leopold ("Leo") Hartmann who came in 1867, and three of Christine's sons who came in 1866 and 1867.

Wilhemina and their six surviving children came with him: Ernestine, Karl Ludwig ("Charles"), Jacob Friedrich ("Fred Jr."), Ludwig ("Louis"), August Leopold, and Max Johann. Adolph was born stateside in 1869, and Louise in 1871. They lived in Wisconsin where Wilhelmina passed away in 1873.

Friedrich then married Christina (Eckert) Sanger (pronounced "singer"), a widow with two children, in 1875. Her son was named Conrad, her daughter Katherine. Friedrich and Christina then had two sons together, Henry and William.

Friedrich moved his family from Wisconsin to Richardson County, Nebraska in 1882, where his brother Leo, sister Christine Ernst, and stepson Conrad Sanger and their families had previously resettled. Friedrich Jr. married Christina Sanger's daughter "Katy" (his step-sister) and settled there, as did Max, Ernestine (Brecht), Louise (Kammerer), and Charles' eldest son, Albert. Most of the Hartmann families dropped the second "n" from their name around the year 1900.

Three of Friedrich's sons, Charles, Louis and Adolph, moved west to south-central Nebraska, eventually settling in Webster County. Their descendants have spread throughout Nebraska and the United States.

Friedrich was said to have died in Sheboygan, Wisconsin, where Wilhelmina probably passed in hospital. But probate records and a newspaper obituary indicate he died at his home in Arago Township, Richardson County, Nebraska.

Friedrich is often confused with several other men of the same exact name who also lived in, or emigrated from, the German states. At least one of these lived elsewhere in Wisconsin; one lived near Kearney, Nebraska; and one well-documented gentleman who lived in Chicago, Illinois was born, and died, in the same exact years as J.F.