William Thornhill (British Army officer)

William Thornhill was an officer in the British Army, notable primarily for his involvement in the early colonial history of New South Wales, Australia. Little is definitively known about Thornhill's early life or military career before his arrival in the colony. His significance stems from his controversial role in frontier violence against Indigenous Australians, particularly the Dharawal people, in the Hawkesbury River region.

Thornhill received a land grant in the Hawkesbury district and, like many other settlers, faced increasing conflict with the Indigenous population who were struggling to maintain their traditional way of life in the face of encroaching colonial settlement. Historical accounts, including court records and settlers' diaries, attribute a leading role to Thornhill in retaliatory raids and punitive expeditions against the Dharawal. He is often associated with the devastating attacks that aimed to displace and intimidate Indigenous communities.

His actions and the violence perpetrated under his command are viewed by many historians as examples of the brutal and often unreported frontier wars that characterized early colonial Australia. The scale and nature of Thornhill's involvement remain a subject of debate and ongoing historical research. While some narratives portray him as a pragmatic officer acting in the face of perceived threats, others emphasize his culpability in acts of extreme violence against Aboriginal people.

The historical record regarding Thornhill is fragmented and biased, primarily relying on colonial sources that often present a prejudiced view of Indigenous Australians. Despite the limitations of the available evidence, Thornhill's name continues to be associated with the dispossession and violence inflicted upon the Dharawal people during the early years of European settlement in the Hawkesbury region. His story serves as a crucial, albeit troubling, element in understanding the complex and contested history of colonial Australia.