The Bourgeois of Ulvila were ordered to migrate to the newly founded city and on 8 March 1558 John III gave the charter of Pori, which read: "Because we have seen that it would be best to build a strong market town alongside the sea, and because we cannot find anywhere suitable for fortifying in Ulvila, we have chosen another location at Pori."
Ulvila linnakodanikele anti käsk vastloodud linna rännata ja 1558. aasta 8. märtsil andis Johan Porile linnaõigused, mille tekst sisaldas ka järgmist lõiku: "kuna me oleme näinud, et parim oleks ehitada tugev turulinn mere äärde, ja kuna me ei leia Ulvila kindlustamiseks sobivat kohta, oleme me valinud teise asukoha Poris".