Within a few days, during which skirmishing parties tracked down and killed many of those who had escaped from Kaiapoi, Te Rauparaha moved on to attack the last remaining Ngāi Tahu stronghold, at Onawe peninsula, in Akaroa Harbour. Construction of this pā, which was defended by about 400 men, was begun by the Māori of Akaroa and the surrounding district after Te Rauparaha's first raids. (Its attractiveness as a defensive position in the warfare of the period is indicated by the fact that the French in 1838 gave Onawe the name of ‘Mount Gibraltar’). Yet in fact it was a deadly trap. For the attack Te Rauparaha divided his forces between the bays on either side of the tongue of land leading out to the peninsula. An unwise sortie of Ngāi Tahu under Tangatahara was beaten back to the pā. Just as the gates were being opened to allow them in, Te Rauparaha and the other Ngāti Toa pressed up close, using a party of captives from Kaiapoi as a screen. With their fire masked by the captives, the defenders delayed too long, and before they could act decisively, some of the northern warriors were inside the pā. Few of the Ngāi Tahu escaped the slaughter that followed.