The "uncle Frederick" that Joseph is talking about in his pension statement is Frederick Starnes, born ca. 1724 and died April 7, 1779 when ambushed by Indians outside Fort Boonesboro (Boonesborough). His father, Joseph Sr., was also killed during this ambush.
The above Frederick Starnes is my 6th Great-Grandfather. If you have any further questions that need to be answered, please feel free to contact me anytime.