Family A 43-24 in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766.
Family B-335 in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766.
Family Rus14-9 in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766.
Family #17 in the 1775 Grimm census.
Catharina Engelhard first came to my attention in the 1775 Grimm Census. At that time, she was a widow with three daughters. Her husband's name was not mentioned, nor was her maiden name. I thought she and her daughters would be the end of the line for this branch of the Engelhards.
Coincidentally, much later, when I was researching other relatives, I found her name again, and further reading led me to her husband's first name, Sebastian. Sebastian was a much less common name during the 1700s, so I thought I might be able to track down information about him in German birth and marriage records.
According to The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766, Sebastian Engelhard was born in 1733, an Evangelical Lutheran from the region near Sulzfeld, Ravensburg, in what is now Germany.  This area in further south and central than most Volga German birth and marriage places I've researched thus far. I assumed that since the couple was married prior to immigrating to Denmark, his wife was probably from the same area. I soon tracked down a copy of their marriage record. Sebastian and Catharina were married on 19 August 1760 in Reichartshausen, Heidelberg, Baden. He was 27 and she was 22. The marriage record also revealed the last name at birth of Catharina as well as her father's name: Graser.
Marriage Record 
The couple had a daughter, Anna Sabina, born in Flinsbach, Heidelberg, Baden.
Birth Record for Daughter Anna Sabina Engelhardt 
There was also a son, Johann Adam who was 2 months old at the time the family immigrated to Denmark, but I have been unable to verify his birth details through online German records.
Much of southern Germany had been ravaged by war and famine, and Sebastian and Catharina had been around long enough to know that nothing was going to change any time soon. They were concerned about being able to provide for his family, as well as to find a way for his children to lead better lives than they had.
In 1759, Danish King Frederick V invited Germans from Hessen and the Palantinate to help settle the area of Schleswig-Holstein, at that time under the control of the Danes.  The king was interested in converting the marsh lands to arable farm land. Germans were known for their good farming skills and for being hard workers, so it seemed like a win-win situation both both Danes and Germans. Sebastian and Catharina decided the opportunity to immigrate to Denmark with their family was too attractive to pass up. The couple immigrated to Denmark with two children: Johann Adam, only 2 months old, and Anna Sabina, by that time 2 years old.
Although he and his wife took their oath of allegiance to Denmark on 29 May 1762, they were considered reserve colonists until the following year. By December 1763, the family lived at 3 Koenigshof in Colony G2 Friedrichsfeld, in the district of Gottorf. 
Despite the positive hype by Danish officials, the marshlands were very inhospitable to farmers. Although the Germans were good farmers with typical farm land, it was far more difficult to convert these former wetlands and successfully grow crops. Most of the German immigrants barely reaped enough to feed their families, let alone to provide food for others. When Catherine the Great invited Germans to immigrate to Russia, the couple decided it offered them a better opportunity than what was there for them in Schleswig-Holstein.
Sebastian, Catharina, and their two children left for Russia at some point after 12 January 1765. The couple and their children moved first to an already established village, such as Dobrinka, where they lived before making the move to Grimm. They had two more children, Christina Elisabeth (born in 1768) and Anna Elisabeth (born in 1774).
Sebastian is not listed in the 1775 Grimm census; his wife Catharina is listed as a widow. Sebastian probably died in late 1773 or 1774, after his wife became pregnant with their youngest child. In addition, neither is their son Johann Adam listed in the 1775 Grimm census. Had he lived, he would have been seven years old. It is likely that he did not survive the journey to the Volga region of Russia or died at some other point prior to 1775.
1775 Grimm Census 
Katharina Elisabeth is not listed in the 1798 census under the surname Engelhard.  She is also not listed by her last name at birth, Graser. It's possible that she remarried and was living in a different household, perhaps even in a different village. If she were still alive in 1798, she would have been 60 years old. It's also possible she had passed away.
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