under its last master albert in 1525, the state of the teutonic order was transformed into the secular duchy of prussia under polish armament. after the death of his successor, the duke albert frederick in 1618, the duchy of prussia became a part of the brandenburg hohenzollern, who now ruled it in personal union. in the treaties of wehlau in 1637 and oliva in 1660, the elector frederick william, the "great elector", succeeded in gaining full sovereignty over the duchy of prussia, whereby he himself became a european sovereign. his successor, frederick iii of brandenburg was crowned "king frederick i of prussia" on 18 january 1701, after the emperor had contractually secured him to recognise him as king of the holy roman empire and in europe. the name and coat of arms of the prussian monarch then passed as a result of the new designation of sovereignty and authority "könglich-preußisch" (royal prussian) to the entire "prussian" state of hohenzollern, which lay within and outside the empire and for which the name of "prussia" prevailed in the eighteenth century.