The fourth pope during the period of the Protestant Reformation, Paul III became the first to take active reform measures in response to Protestantism. Soon after his elevation, 2 June 1536, Paul III summoned a general council to meet at Mantua in the following May; but the opposition of the Protestant princes and the refusal of the Duke of Mantua to assume the responsibility of maintaining order frustrated the project. Paul III first deferred for a year and then discarded the whole project.