Do you have a general birth or death date for Fritz since posting? There were notices in the local German language papers for a Fritz Gottschalk in 1904 (69 yr). I also indexed probate notices published later that year for a Friedrich Gottschalk.
There are about 190 occurrences of Gottschalk in the current version of "Milwaukee's German Newspapers; an index of death notices and related items" (1844-1950).
For more specific information contact:
Gary Rebholz, compiler/editor
Indexing Milwaukee's German newspapers continuously since 2007... helping to access our historic German-American culture.