Joseph Mathiesen was born in Copenhagen, Denmark, on 7th January, 1840. He emigrated to America when he was nineteen years old and settled in Evansville, Minnesota. In 1861 Mathiesen married Judith Johnson.
On the outbreak of the Civil War joined the Scandinavian Regiment that was commanded by the Norwegian, Colonel Hans Heg. Although Mathiesen had no military experience, Heg appointed him Captain of Company B.
He commanded Company B for the rest of the war participating in the battles at Perryville (October, 1862), Murfreesboro (December, 1862), Chickamauga ( September, 1863) and Pickett's Mill (May, 1864).
After the war Mathiesen became a successful businessman in Evansville. Joseph Mathiesen died on 1st March, 1925.