In 1988 my father received this information from a woman in Germany, who researched the Lutheran Church records in Landkirchen and in the Burg (town) on the Island of Fehmarn, for him.
George Jacob Kortum, Schiffer in Lemkenhaffen
B. Lemkenhaffen March 4, 1846
In Landkirchen Dec 12, 1867 To:
Johanna Maria Rasmus (Rehr) (I have more about this)
B. Landkirchen February 2, 1845
They came to the United States in 1881.
Their children are in Church Records as follows:
1. Emma Amalie Agnes
B. Landkirchen January 1, 1868
D. Landkirchen March 1, 1869
2. Jacob Friedrich
B. Landkirchen April 1, 1870
B. Landkirchen May 9, 1871
4. Carl Jacob Peter
B. Landkirchen October 6, 1872
5. Meta Margaretha
B. Landkirchen November 25, 1874
6. Johanna Amalie Caroline (My Great Grandmother)
B. Burgstaaken May 9, 1876
D. February, 1965 Kalispell, Montana
7. Agnes Dorothea Catharina
B. Burgstaaken June 15, 1877
8. Catharina Doris
B. Burgstaaken September 3, 1878
B. Burgstaaken August 27, 1880
I have more information on some of these people, but mostly on my great grandmother, and her descendants.
I do not know anything about the following children that Joseph Swallow found listed in the 1900 Federal Census for Iowa:
B. October 1885
B. November 1887
It is my personal belief that the 19 year old Fred shown on the census is Fritz. (Possibly his name was Jacob Frederich also?)
Just a thought, but I believe the church records more or less bear this out.