Analyse if all the fields found in DB tables have been covered in ontology design.
deathPlace & birthPlace as Resources instead of strings, use existing publically available Place resources from DBPedia. (Ex: http://dbpedia.org/resource/Berlin)
Use foaf ontology: soldier should be a type of foaf:Person, also analyse and reuse properties like lastName/firstName available in foaf. (See: http://xmlns.com/foaf/spec/#sec-glance)
Add German language labels for classes. Make the labels more readable.
Changing the URL prefix.
Troubleshoot the problem with special characters in the output TTL file.
Remove Soldier resources with names in URI, only use ids. Possibly do this for other resources as well.
Introduce more subclasses in the ontology for correct assignment of data properties.
Discussion: Removing classes starting with _ as suggested by Adrian.
Create an RDF model of the historians dataset.