The Diet of Worms was a council convened by Emperor Charles V which ran from 28 January to 25 May 1521 in the Free Imperial City of Worms, a town located in an area part of modern Germany – as German unification was not to occur the 19th century, one cannot describe Worms during the Reformation as being located in Germany. The Diet concluded with the proclamation of the Edict of Worms.
The Diet was convened in response to Martin Luther, who had presented his 95 theses for dispute at the University of Wittenberg (not nailed them to the cathedral door, as in popular myth). A 1520 Papal Bull, Exsurge Domine, condemned Luther, but Luther was quite popular and continued preaching and writing. The Edict of Worms supported the Pope and condemned Luther as a heretic.