William Joseph Punch was believed to have been born in the Bland River region of New South Wales around 1880. Presumed to be a Wiradjuri man, William was taken in by the Siggs family of Goulburn after frontier violence resulted in the murder of his family soon after his birth.
He attended the local school where he was a good student, a keen sportsman, and an accomplished musician. William was working as a station hand when the First World War broke out. He enlisted in the Australian Imperial Force at Goulburn on 31 December 1915.