William Willshire was the son of James Doughty Willshire, schoolmaster, and his wife Emily Elizabeth, née Schlenkrich. He joined the South Australian Police Force in 1878 and was posted to Alice Springs in 1882, gaining rapid promotion to first-class mounted constable in 1883.
In 1891 Willshire was tried for the murder of Aborigines but was not found guilty. Accounts given by Willshire in his writing and in secondary sources vary widely in the interpretation of events and the defendant's general policing practices.
