 Hobson, meanwhile, was becoming alarmed at the news of the company's growing assumption of power.He learned of their bid to imprison a Captain Pearson of the barque "Integrity" and that on 2 March they had raised the flag of the United Tribes of New Zealand at Port Nicholson, proclaiming government by "colonial council" that claimed to derive its powers from authority granted by local chiefs.Interpreting the moves as smacking of "high treason," Hobson declared British sovereignty over the entirety of the North Island on 21 May 1840, and on 23 May declared the council illegal.