Etymologically, it is the way (Weg) or distance which you can pass within one hour (Stunde).

In this 1850 military book, the Wegstunde is given as "generally equal" (I read this as: "roughly equal) to one French lieue or 4444 meters, or 6000 paces (Schritte):

https://books.google.de/books?id=EwMSqsid3I4C&pg=PA16&dq=schritt