1804 Risdon Cove massacre

On 3 May 1804, an estimated 300 Aboriginal people from either the Oyster Bay (Paredarerme) or Big River nation approached the recently established British outpost at Risdon Cove on the Derwent River, Van Diemen's Land, while engaged in a kangaroo hunt. According to available accounts, some in the group were upset by the presence of the colonists, but there had been no widespread aggression toward the settlement prior to the killings.

Approximately 75 colonists and soldiers of the New South Wales Corps, under the command of Lieutenant William Moore, mistakenly believed they were under attack. Both the commandant of the outpost, Lieutenant John Bowen, and the Lieutenant Governor of Van Diemen's Land, David Collins, were absent at the time. Moore ordered three sorties against the Aboriginal group beginning at around 11 a.m. The soldiers and colonists were armed with Brown Bess muskets and were also ordered to fire grape shot from a 12-pounder carronade, a naval cannon salvaged from HMS Investigator, to disperse the group. The final shot from the carronade was reportedly heard three hours later in the neighbouring settlement of Hobart, where clergyman Robert Knopwood recorded hearing the "roar of the cannon at Risdon at 2 p.m."

No colonists or soldiers were harmed. Three Aboriginal Tasmanian bodies were recovered from the scene, and colonists believed more had been wounded, having seen one person carried away bleeding. Reverend Knopwood believed at least five or six people had been killed.

An infant boy, aged about two to three, whose parents had reportedly been killed in the incident, was taken by the colony's surgeon, Jacob Mountgarrett, brought into British colonial society, and given the name Robert Hobart May. Mountgarrett also obtained the body of one of the deceased Aboriginal men and dissected it; the skull and bones were shipped to Sydney in two casks.

Five days after the incident, Lieutenant Governor David Collins ordered the closure of the Risdon Cove settlement, relocating settlers to Hobart and sending the outpost's soldiers back to Sydney, citing a lack of discipline. Lieutenant William Moore was acquitted of wrongdoing at a court martial in September 1804 and was later promoted to captain in 1809. In 1819, William Charles Wentworth attributed subsequent hostility from Aboriginal Tasmanians toward colonists to the "unmerited and atrocious act of barbarity" committed at Risdon Cove. A 2022 publication questioned whether eyewitness Edward White was present at the event; this claim has reportedly been rejected.