Johann Georg Robertus (son of Hans Georg and Magdalena Robertus) was born on 13 December 1742 in Schriesheim. He immigrated to Denmark (Schleswig-Holstein) where on 12 November 1760 he married Apollonia Barthold (born 15 May 1733 in Lampertheim, daughter of Wendel and Gertraud Barthold) in Thorning, Jutland.
The baptisms of two children were recorded in Danish records: Maria Catharina, baptized 24 Spetember 1761, and Maria Elisabeth, born 30 September 1762, both in Friderichsheede, Karup Parish, Viborg Amt.
In 1764, the family immigrated to Russia, arriving in Balzer on 28 August 1765. They and two daughters are recorded there on the 1767 census in Household No. 9.
- Lang, Gerhard. German Colonists of Denmark on the Volga .
- Danish parish record extractions by Wayne Bonner and Mike Meisinger
- Pleve, Igor. Einwanderung in das Wolgagebiet, 1764-1767 Band 1 (Göttingen: Göttinger Arbeitskreis, 1999): 74.