| Site Name | Cockatoo Valley, Hollow Tree |
| Aboriginal Place Name | |
| Language Group | Oyster Bay |
| Colony | VDL |
| Present State/Territory | TAS |
| Police District | Oatlands |
| Latitude | -42.532 |
| Longitude | 146.943 |
| Date | 23 Oct 1828 |
| Attack Time | night |
| Victims | Aboriginal People |
| Victims Killed | 6 |
| Victims Killed Notes | Killed: M 6 - unspecified - a considerable number, F; Probable: M F; Possible: M F; Wounded: M F |
| Attackers | Colonisers |
| Attackers Killed | 0 |
| Attackers Killed Notes | Killed: M 1 F2 W F4 |
| Transport | Foot |
| Motive | Reprisal |
| Weapons Used | Firearms, muskets |
| Narrative | In two separate attacks over 2 weeks, Oyster Bay warriors killed Anne Geary and Mrs Gough and then Mrs Langford's son, John. A reprisal party 'fell upon' the warriors' campsite near Cockatoo Valley at 11pm and fired after them, 'killing and wounding a considerable number’. |
| Sources | The Tasmanian, October 31, 1828 - https://trove.nla.gov.au/newspaper/page/25173660; HTC 18 October http://nla.gov.au/nla.news-article4220434; November 1, 1828 - https://trove.nla.gov.au/newspaper/page/641811. (Sources PDF) |
| Corroboration Rating | ** |
