Johann Bernhard Posserth, son of Heinrich & Susanna Margaretha Posserth, was born and baptized on 20 November 1733 in Graben, north of Karlsruhe. He married Anna Maria Wacker on 3 March 1761 in the Graben Evangelical Church.
Johann Bernhard & Anna Maria immigrated to Denmark (Schleswig-Holstein), departing from Altona, Duchy of Holstein, on 5 May 1761 under the leadership of Andreas Kirchhof. They arrived in the city of Schleswig, Duchy of Schleswig, on 9 May 1761.
In 1764, they had a boy who was named Heinrich. The Bossert family lived in Denmark until 12 January 1765 when they immigrated to Russia. They arrived in the Volga German colony of Stahl am Karaman on 9 July 1766. They are recorded there on the 1767 Census in Household No. 3.
Son Heinrich and his family are recorded on Stahl am Karaman 1798 Census in Household No. Sk36.
- Eichhorn, Alexander; Eichhorn Jacob & Mary. The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766 (Deiningen, Germany: Steinmeier, 2012): 253, 360, & 686.
- Mai, Brent Alan. 1798 Census of the German Colonies along the Volga: Economy, Population, and Agriculture (Lincoln, NE: American Historical Society of Germans from Russia, 1999): Sk36.
- Parish records of Graben (LDS Film No. 1238319).
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 4 (Göttingen: Nordost-Institut, 2008): 192.