The killing of George Layman did not emerge from nothing. Conflict between Wardandi Noongar people and European settlers in the Busselton district had been escalating for months. In February 1840, three young Wardandi men -- Nungundung, Duncock, and Gerback -- killed Henry Campbell, a settler labourer on the Collie River, because Campbell had badly beaten Duncock. Academic Jessica White has argued the motive also involved the rape of one of Gaywal's daughters. The resident magistrate of the Leschenault district, Henry Bull, flogged the three men and released them. John Bussell, a prominent settler, was furious at what he considered lenient treatment. When he encountered Gaywal's son-in-law Nungundung in December 1840, Bussell had him arrested, held him at his property Cattle Chosen, and sent him to Perth for further punishment. The arbitrary re-imprisonment of Nungundung enraged the Wardandi community. Threats were made to settlers throughout the district in the months that followed.

After Layman's death, John Bussell and Captain John Molloy, the district's resident magistrate, organized a punitive party. They coerced a Noongar constable named Bun-ni into serving as guide by holding him at the Bussell residence until they were satisfied of his cooperation. On the night of 23 February, thirteen settlers set out toward Mollakup, where Gaywal was believed to be hiding. After a day and night of tracking through sandhills, they attacked a group of Noongar people sheltering near Lake Minninup, killing at least seven and capturing thirteen women and children. Gaywal was not among them. Bussell and Molloy officially reported only five dead. A second expedition, led by Vernon Bussell, took more Wardandi hostages near Mollakup. When a third party arrived with reinforcements and ammunition, the hostages fled in terror and two Wardandi men were shot. The settler community had mobilized from Wonnerup, Capel, Busselton, and Augusta. Warren Bert Kimberly, writing in 1897 after interviewing both settlers and Noongar survivors, described it as "one of the most bloodthirsty deeds ever committed by Englishmen."

The massacre was, in Kimberly's word, "systematically downplayed." Charles Symmons, the colony's Protector of Aborigines, arrived during the aftermath and was roundly abused by the settlers for attempting to intervene. Bussell and Molloy submitted two reports to the colonial secretary stating that eight Wardandi people had been killed across the three punitive events, but the true number was almost certainly far higher. Large numbers of Wardandi people were simply unaccounted for afterward. Governor John Hutt oversaw the Swan River Colony at the time, and the settler community closed ranks against further inquiry. Molloy's letterbook for February 1841 contains no recorded correspondence -- a conspicuous gap. Four pages are missing from Fanny Bussell's diary for the same period, an absence historian Edward Shann attributed to the desire to conceal the settlers' argument with Symmons. A descendant of John Dawson, one of the labourers present at Layman's death, later acknowledged that something dreadful had occurred, something that "seriously affected the moral of the whole community."

For most of the next 178 years, the Wonnerup massacre existed primarily in Wardandi oral history and in Kimberly's largely forgotten 1897 account. The Waadandi Doonan people preserved their own version of events, including the understanding that the conflict between Gaywal and Layman involved a Wardandi woman -- a dimension absent from settler accounts. Academic research in the late twentieth and early twenty-first centuries began to reconstruct the full picture, drawing on both colonial records and Aboriginal testimony. In January 2019, the City of Busselton unveiled a bronze statue of Gaywal on Queen Street, the fifth sculpture in artist Greg James's Settlement Art Project. The figure stands in a town whose name derives from the Bussell family -- the same family that led the punitive raids. That juxtaposition is not accidental. It acknowledges that the history of southwestern Australia contains both the settlers and the people they dispossessed, and that remembering the violence honestly is as much a part of the place as the farmland and the bay.