She rejected the Anglican Church which Henry had instituted and tried to turn England back to Roman Catholicism. This effort was carried out by force and a number of noted Protestant leaders were executed. This earned her the title of 'Bloody Mary.' Modern scholars have pointed out that fewer Protestants died under Mary than Catholics under Elizabeth, but admit that, averaged over a length of reign, the Marian death toll was indeed higher. Her restoration of Catholicism was remarkably successful in some ways; where only one bishop - John Fisher of Rochester - had resisted Henry's changes to the point that Henry had him executed, most of Mary's bishops refused to conform to the restored Protestantism under Elizabeth I and died under house arrest.
Mary also set in motion currency reform to counteract the dramatic devaluation of the currency that characterized the last few years of Henry VIII's reign and the reign of Edward VI. Mary's deep religious convictions also inspired her to institute social reforms, although these were largely unsuccessful. She was deeply unpopular, but did not last long on the throne being succeeded by her younger sister Elizabeth I, who quickly undid most of Mary's changes.