airwalkrr
Adventurer
When I came up with the idea for Helmut, I had the notion that he would have fought in some border conflicts against the orcs of the Pomarj. I picture him right about 30 years old, so he would have been a veteran during the orc invasion, which fits with his rank of sergeant leading a platoon of soldiers. Looking at the map of Greyhawk, I think that would make the Principality of Ulek his most likely homeland, but I'm not sure what the details are of the orc invasion you mentioned.
Just FYI the Principality of Ulek is a dwarven land. Not many humans live there. The Domain of Greyhawk battles against the Pomarj orcs with a great deal of frequency however. They raid all the way up the Wild Coast.