The Diet of Worms was a council of the Holy Roman Empire in the city of Worms. The council was held because of Martin Luther and the Protestant Reformation. It lasted for five months in early 1521. The Emperor, Charles V led the council. Other councils (called Imperial Diets) were held in Worms in the years 829, 926, 1076, 1122, 1495, and 1545, but the most important Diet of Worms was in 1521.