On 10 July 1863 Grey ordered the invasion of the Kingite territory, claiming he was making a punitive expedition against Rewi over the Oakura ambush and a pre-emptive strike to thwart a "determined and bloodthirsty" plot to attack Auckland. On 12 July General Cameron and the first echelon of the invading army crossed the Mangatawhiri Stream - the Invasion of the Waikato had begun.