The enforcement of the ban on the 95 Theses fell to the secular authorities. On 18 April 1521, Luther appeared as ordered before the Diet of Worms. This was a general assembly of the estates of the Holy Roman Empire that took place in Worms, a town on the Rhine. It was conducted from 28 January to 25 May 1521, with Emperor Charles V presiding. Prince Frederick III, Elector of Saxony, obtained a safe conduct for Luther to and from the meeting.