Geni.com gives his year of birth as 1892. Denkmalproject.com lists a Hans Schlesinger born 1891 in Oswiecim and living in Breslau; Hans' brother Gerhard is known to come from Oswiecim, and the family's death notice cites an address in Breslau so this is likely to be the same person.

According to the death notice, Hans was serving as a pharmacist in a field hospital during WWI.